I actually have a detailed email that I sent out to some students that has tons of details and links. I can email it to you. I can post it here but it is pretty long.
First swing - Your hand/arm does not pass your left shoulder but instead you are allowing your waist to over rotate which is giving you the impression that you are completing the follow through.
Second swing is almost the same. Your right hand is not going behind your body and this is what I mean about wasted energy by stopping your swing path.
Keep in mind that right now I am only talking about the follow through and not your actual shot. Things need to be broken down.
Here is an example of the correct form regarding follow through.
Watch at 9 seconds. The 4th time Federer swings the racquet. He is hitting pretty gently but look at the follow through. It is wrapping around his back. The racquet head goes so far behind him that it is almost parallel with the back of his head. Your racquet is not even passing your left shoulder. Watch your video and pause at the very completion of your first or second swing and then pause Federer's video at the completion of his 4th swing. The difference is vast. Your problem is mostly mental and I went through the exact same phase. I felt like I was really following through but I was stopping very short like you are. Once you start pushing yourself to really wrap the racquet around you end up getting tons of extra pace with no extra effort. When the form is correct you will be able to hit blistering shots that look effortless.
Let me know about that write-up if you are interested