As soon as it gets split off from google and they no longer have the money machine to fund them and have to fight on a level regulatory-monitored ground for ad revenue you can bet your ass it will.
For every year that passes, storage becomes cheaper, but the total size of youtube's video repository grows. I wonder what the net effect of all that is in the end. Ever increasing costs? Or maybe it kinda evens out.
Interestingly, if storage cost decreases geometrically over time, then the total storage cost of storing a video for all eternity is finite.
Though what I was commenting on here wasn't so much the cost of storing a video at all, but storing it in 'warm' enough storage that you can load it really quickly.
Can you post your source? Last time I checked (and quickly checking around now) I didn't see any announcement from Google about Youtube being profitable.