Interesting, I recently had the opposite experience. Wanted to enable hw decode on an older Intel system and only got it to work on Firefox. Tried several different instructions from the web on how to force chrome to ignore any blacklists for drivers or anything, but still no luck.

Oh and a while ago I noticed (on a more modern system) that enabling hw decode makes chrome ignore the aspect ratio of the video and displays it like the pixels are square. Again Firefox handled it fine.

(Linux, h264 in both cases)