'Improvise, adapt and overcome' (shrug)
Interesting vid, but it 'solves' a lot of self-created issues. If you use a cap or strap wrench to bear down, you get the friction rub-off debris mentioned in the vid. They're HDPE-2, they're soft plastic. Make them tight enough, you crack the lid. You don't have to make them more than hand-tight.
Guy says 'I have expensive **** in my vehicle I can't get wet, but I chose to lay my MWCs on their side. Wrong packing config, wrong water storage solution, etc etc.
The answer to the vent cap is remove it and replace it with a bolt / nut. Seal it shut.
Furthermore your pointing out that there's no bursting spec on a water container is funny / ironic. The absence of a spec doesn't mean it's weaker, it just means nobody cares if a WATER container bursts, it isn't a hazard considered worthy of a specification. 'The Perils of Di-Hydrogen Monoxide'!!1!
Even funnier is the guy in the subsequent video demonstrating fitting a self-venting spigot to his MWCs who with a straight face advises the use of a lithium lube on the fittings of his potable water container. Talk about missing the point of carrying potable water. Lithium is a toxic metal. and like a lot of meds it's safe in infinitesimal doses and will kill you in heavier dosages. NOT something you should use on your water supply.
https://www.youtube.com/watch?v=_OH11sNFjHI
I used MWCs and MFCs for years in the Marines and since. I own LCI MWCs. They don't leak when new / unabused. Filled, on their side, with my fat *** jumping on them, they don't leak.
http://www.expeditionportal.com/forum/threads/135929-Jerry-Can-MWC-MFC-stowage-box-build
The pile of junk I used to drive around back in those days. The only cans that leaked then were those whose fittings looked like they'd been chewed by somebody's dog.
I'm sanguine about making it work. It's worth $50 or more per container to me to give it a try with the viton gaskets. Guess I'll go figure out the right-sized gaskets myself and convert one as a proof / example.
I will speak of it no more. The determined resistance to thinking outside the box / lines is just too dissatisfying. Stay within the lines, the lines are your friend.