First, no idea if there's issues in the footwork department, since this is strictly about the swing. So, if there's still issues with the unit turn or feet, that's still highest priority. That said, the stance looks appropriately open and it looks like you're starting to sit and lift.
One thing that helps is to, while practice swinging this FH, to hold the racquet with just the thumb, 3rd and 4th fingers. This will expose problems in mechanics more clearly.
Onto the clips . . .
C14-15, D-12-13 show that you're getting good extension into the shot, while the arm remains relatively close to the body. That's pretty close to what an ideal "regular" WW FH should look like. There may be a slight hitch here, but I'm not quite sure. Generally this is the right look, though. As you rotate, your racquet will spring in a straight line toward the ball.
1) Your left-arm is good, but make it a little higher, hand above shoulder level. Also, try holding the racquet with the 1-3-4 fingers during shadow swinging.
2) Set C5/D6 as your height of takeback.
In other words, when the racquet is inverted and on edge, let that be the "height" of your swing. This will be the point where you stop actively taking the shoulder back, and where you start letting gravity do the rest.
In your clips, I think you have C8/D7 as your height of takeback. That is you're still continuing to actively turn the shoulder and pronate the forearm/invert the racquet beyond the point when the racquet is inverted and on edge. This is technically correct in that Federer (and Safin) often go beyond that point (as is plainly shown in the C5-C8 Federer shots), but you don't want to try that now.
3) Try a basic FH first by letting the arm drop without any forearm rotation
In other words, an Agassi-style takeback. From your new height of takeback, just let the hitting arm drop with the racquet still on edge. Your wrist may be somewhat laid back (so there's not a lot of "wrist action" here.) Let the body initiate the forward swing
This is kinda the "reference FH", in that you should still get a WW FH with plenty of wiper movement and extension of arm into the ball. You should see an end result at POC like C14-15/D12-13, but with much better wiper movement and thus better spin. You should always use this FH to work on new elements first, and then test if you get a "springing" WW forward swing.
4) Work on the wiper action with the basic FH
It's just easier to get that down now, because again all of the techniques up to now will still apply later.
The key thing about the WW FH is that, whether you have a little bit of wiper action or a lot of wiper action, the motion of the body and hitting arm doesn't change. In other words, you at no time "actively" make a wiping motion to put extra spin on the ball. Whatever you do to faciltiate wiping action should not change your basic swing.
Basically, you want your body and hitting arm to go forward, while your wrist stays back. Visualization techniques help with this. I like to imagine that the right side fence is somewhat close to me. You can imagine that you're swinging out of a slot. You can consciously keep your racquet back "longer" as you initiate the forward swing. Whatever it takes to get bigger wiping motion without changing the basic swing.
Once you get that down, you just commit that to muscle memory.
Now onto the weird stuff . . .
5) C11-12,D10-11 marks the transition beween the backswing and the forward swing.
D10-11 suggests that you're still opening up the racquet by actively supinating the forearm/opening up the racquet face (i.e. "patting the dog" at the last minute.) Which is how most people execute their FHs, but not Federer.
Your hitting arm between D10 and D11 has't move forward all that much. Contrast that with Federer's hitting arm, which has moved forward a lot between the two clips, and notice how much his wrist is laid back.
This indicates that, from that position you see in D10, Federer then drags his arm forward in a straight line, letting torque "pivot" the racquet around the wrist and open up to D11. If you watch the relative height of his elbow between C11 and C12, he doesn't let the arm "scoop" from down to up. He's literally dragging his arm in his forward swing. Now if you look at your elbow, you do let the arm scoop. That scooping motion is a normal part of the FH, but not of Federer's FH.
5A) Holding the racquet, practice dragging your arm in a straight line back and forth, letting the racquet face open up and close around the wrist. Avoid the temptation of "scooping" under this line to open up the racquet
This technique will feel a little strange, and it isn't ideal in a normal FH. But this "drag forward swing" is important before you get to the next step. Obviously, you need to have a looser wrist to facilitate this.
6) The racquet drop (where you let gravity do its thing while you pronate the forearm slightly) from C9-11,D9-10 is pretty good. The thumb-wrist line does open up a bit too much.
There's two different ways you can correct that:
6a) If you adopt the new height of takeback from step 2, then just make sure the end of your right thumb is always pointing toward the net as the racquet drop, keeping in mind to relax the wrist. In fact, the combination of the two helps to set up the right amount of forearm pronation as the racquet drop from gravity.
6b) As the racquet drops and the forearm pronates, you'll notice that the racquet head come in closer to the right side of your body through the whole racquet drop. If it doesn't, then either the wrist is not relaxing or the thumb-wrist line is opening up too much. This isn't something you force, but a sign that everything else is working.
Between D9 and D10, you can observe that Federer's racquet head is coming toward his body as his racquet drops, whereas in your drop, the racquet head is staying far away from the body.
7) It helps to just practice stages C9-12,D9-11 together. That is, work on feeling out the arm motion of the racquet drop and then the initiation of the forward by "dragging" the racquet. You know you have something if the arm springs forward at an accelerated rate with aggressive wiping action. And this occurs without really a full shoulder turn or use of the body's kinetic chain.
The arm just does this by itself: the racquet head "snaps" forward like a whip, and the arm "slings" forward.
