I'll just point out the most obvious things one forehand aswell as backhand that i saw.
In general i like your Backhand better technique wise, especially your slice looks nice.
As Moz stated before you don't go into a readyposition. You just stand to the ball the way you walked towards it.
You don't bend your knees, but in order to do that you need to improve your preperation first.
Look at your forehand and backhand in comparison. You will notice that on the backhand side you rotate your body more, and you also transfer your weight into the ball better.
On the forehand i suggest you to practice either doing a little hop into the ball as you hit, or just walk through it, doing the "walking step", in order to improve your weighttransfer.
In order to fix the issue with your preperation let your partner hit far into your forehandside, with not too much pace, so you'll have to walk up to it. Then when hitting, take an open stance and bend your right knee. Rotate your body about 90° clockwise and perform your stroke. When practicing just put more focus on your stance and kneebending than you normally would.
I like your backhand, it looks solid. Just one real easy improvement i'd suggest is the swing. Something many people do is start their backswing very high, usually because they learned that way on the forehand side and transfer it to the backhand aswell. With a two-handed backhand however that is not ideal, as it doesn't give you the extra acceleration it does on the forehand side, but makes your timing much harder. Maybe try to just take the racquethead back at about the height of the waist. You don't need to take it back far or high, just something like 45° counter-clockwise. To see that in performed in perfection look at Safin/Nalbandian Backhands.
I hope my feedback helps.