Noun for "playing of the video/audio" object
The noun form of 'to play' is play. So you could say:
Average plays per hour
Total plays
You can play a song (or another piece of audio media), or a movie/video. iTunes also refers to a play count for how many times you have listened to a song, or watch a video. So you would say:
In iTunes, my favorite song has a play count of 4,000.
I would recommend plays over play count, however.
You might consider using runs as a noun here.