I have a livestreaming video on a cable for an engineering underwater rov project. It has an o-ring, but it isn't that waterproof. How can I water proof it for cheap. I was thinking of dipping the cameras in epoxy, bt was wandering if there are any better ways.

You can get liquid electrical tape, and brush it around the O ring, its what I used when water proofing my rock crawler electronics, or I have seen stuff called plastic dip, might also work.

I uses an old servo and dipper it entirely with CorrosionX. Left it to dry then left it in a cup of water for abt 30 mins. It was still working.

Thanks for the sugestions, I'll probably use the plasti dip, but want to buy the corrosionx for my rc car and fishing reels.

CorrosionX is really good. Use it on guns, cars, anything metal. One thing I've started doing recently is applying it to a microfiber cloth and using that cloth for wiping things down. It applies a really thin layer so you're not wasting it.