I own a Vault, and I get a lot more burn time than that video reflects.
My normal fuel loading consist of ~6 pounds of RO lump and a couple of pounds of mesquite chunks. This fuel loading will easily maintain my vault at 250 for 14+ hours (dry). I burn this loading in a horse shoe configuration.
You also need to consider the "meat" loading in this whole equation.....
My normal meat loading will usually be several briskets, butts or a half dozen racks of ribs or more. These smokers usually cook faster than an off-set type smoker and several 12 pound packers will be done in ~6-7 hours. So, I'm "over" fueling my pit a bit. I really like loading the lump/wood one time for anything I cook. I haven't seen an off-set be able to do as well, generally speaking.
As far as any corrosion.... I've had my Vault for about a year and a half and have not seen any type of corrosion. They seem to be well thought out as to where they placed the stainless steel in the robust construction of these smoker.
As for me.....All things considered.....I can honestly say, buy a Vault or Safe with confidence.