Very useful - even if you are under coaching supervision.
GNAS performance coaching courses use video a lot and it is very telling. Ideally you need a way to get the video onto a comuter for frame analysis, but just the tape is good if you can't do this. Try taking your shirt off and shoot some video from the back to show your shoulder positions and which muscle groups are working (or not in my case!). There are planty if pictures in taxtbooks as to o how posture and draw should be executed - you can compare yourself to these even if you have no coaching support.