Hi Rhida, it's a pity that the video is out of sync. Let me say that this lesson is a very good choice to work on your rhythm since I think that it's one of your weak point that need to be worked. This lesson is not sounding bad, you are playing the strum that have to sound at the first beat of each measure tight, but then the groove is a bit irregular, it also sound a too rigid.
Based on what I can see in your video, you are not following the 8th note groove with an up and down movement of your right hand. Check the original lesson and notice how the instructor keeps on moving the hand up and down even when he is not reaching the strings. This technique helps us to keep a groovy and tight tempo over the drum rhythm. Also, you need to let your right hand move more relaxed and from your wrist in order to apply this technique.
Please keep on practicing this lesson and let me know if you could understand what I mean.