Ultimately content must reside in someone’s account. If you never privately delivered the video to anyone, and it only exists in your account, it is permanently deleted from our servers upon deletion.
If the video exists in someone else’s account besides your own (i.e. it was privately delivered to them), then the video cannot be deleted. This allows you to make any necessary updates to the video if the client requests them in the future.
If the video is part of a presentation, you will be prompted to first remove it from the presentation before it can be deleted.