Had a GoPro for a while and managed to get a semi decent video mounted on the scope,
but its bulky and not set up for narrow field of view, longer distance shots but does the job

Just bought one of these on a whim - a 13 whim
have to say its pretty bloody good
less than a fifth of the size, bit fussy to use as no screen menu but once on the picture quality is decent and more importantly the longer range image is in focus and useful

SQ8 Mini Full HD 1080P DV Sports IR Night Vision DVR Video Camera Camcorder SP | eBay

comes with a crocodile clip mount which will need improving but for fair weather stalking video it looks just the ticket!
and for 13 you could have several going at once!