video rotation

No, it also works with multi-slide synchronized videos. On each slide, you can rotate the video segment. I like to show this in my classes to illustrate the fact that on every slide where a multi-slide video is used, you can resize, rotate and perform other changes to that portion of the video. It makes for a fun visual but also to show how you can reposition, resize, and rotate video to accommodate other objects you are synchronizing. 

That is only possible if you use event video, it has the rotate button on top:

If you want a precise angle, use the Options tab of the video Properties panel: