The videos look like they're using a moderate level of power. Probably nowhere near BOTN level.
For metal thickness, you're probably looking at 16ga plate for most of your body. But I highly recommend talking to the group you're joining, since they probably already have a set of rules and/or guidelines around this, and I'd hate for you to buy something and then find out it's against their rules.
I'll comment on swords also, with the assumption that you're looking for that too. But again, you'll want to talk to your group about this as well.
Since the swords are striking armor a lot, you definitely want something durable There are many options out there that will work for this.
From Albion, the Meyer is really meant more for unarmored combat, but could still work. It's a little more expensive though. So is the Albion Liechtenauer. That one is meant as more of a stage-combat, or half-swording weapon, rather than one you're going to do powerful strikes with, as it has fairly thin edges.
From Arms and Armor, the Fechterspiel is a good sturdy longsword, at a similar price point to the Albion Meyer.
But there are much more affordable options out there. I'd consider Darkwood Armory and Ensifer as really good affordable choices. There are probably many others I'm not thinking of at the moment too.
