Hello. can you select the video (not play just open it) and in the top right tap on teh menu and seelct 'info', and let me know the fiel type and resolution? Not all video types are supported for playback in Cloud even though we will save them for you. Also let me know if the video is both in the Cloud and locally on the device, or only in the Cloud (Local Copy removed).
You can also use the "Send Feedback" option in the Navigation Menu to submit a trouble ticket Directly to the Cloud Support Team, and include screen shots of the error and additional information pertaining to the problem.