FWIW it sounds plausible. I watched a few YouTube videos myself a day or two ago, and I think it was then I noticed a problem with my battery. However, I do expect moderate battery drain in general, given how much streaming I do (and also driving or walking around without remembering to disable GPS when I don't need it. Therefore I didn't actually check the battery status until earlier today, which is when I noticed Mediaserver was the main culprit.
Another possibility was that I used the camcorder a day or two ago as well.