Hi,
First post in the striking forum so I don't have any cred around here. But here to put in two cents in addition to the comments above and hope you find it useful.
The sidekick needs to be more... compact. As you turn, try to chamber it all the way up to your sternum. Release it out from there and bring it back in quick. Though your feet are not visible, from watching your plant leg knee, I think that your plant leg heel is not positioned correctly. Think of using the plant heel as a pointer. If it is not pointing directly back to the target, your hips just wont' turn enough and you won't be able to generate enough power. Also after impact, draw your leg back in a bit instead of just letting it fall to the ground. Much similar to the return phase of punching the poster a few above mentions. In the round kick, more hip turn is also required as mentioned above. Again I think this will be fixed if you rotate your base foot more.
Punches have a elbow flaring problem. What I call the chicken wing punch. Try to keep your elbows tight in the release phase. A bit too much of a forward lean also in the punches. Especially in the combos where you are reaching a bit. Movement is a bit stiff and needs more rhythm or flow as they say. Bend from the knees and not from rounding the back. Try to bob by leading with the shoulder if that makes sense. More bag work should fix that I should think.