How damage work in this game ?

[Lu Bu]

So... I wanted a burn build with the new shotgun, i have found a very recent video on youtube, i have the same gears, the same mods with the same sub states, without buff he deal between 50 to 80k dps (and something like 150 to 200k buffed). Me, again with the exact same build, i deal between 20 to 30k dps. How is that possible ? (Sorry for my english)

[Big Boom Boom]

There are a lot of tricks here
BP level, most people now make video of 6 stars. The Pyroclasm rely on Weapon DMG so BP level is very important.
Burn build is also very reliant on Pyro Dino for the showcase DPS, otherwise they sucks. Pyroclasm is the only Burn weapon that do decent DPS without Pyrodino. What the Dino does is everytime you proc Burn you have a chance to do big explosion DMG, on top of increase your Burn DMG %. For example I do a KVD Boom Boom build, dps without Dino is around 40k and flip the Dino it becomes 120k easy.
Pyroclasm showcase video starts by Reloading the Dragon Breath ammo, wait for DPS reset on dummy before starts shooting to make sure you get best possible DPS on the dummy.
Do you actually have the same substats? Just having Crit DMG is not the same as having maxed out Crit DMG and Weapon DMG on the substat.
Ping can definitely affects your DPS. As an Australian playing in ASEAN server, my ping is 100ms when server don't lag because of people teleporting into Chaosweaver. So my DPS is always a bit lower than someone in ASEAN.

My dps with Dino. I'm doing more Crit base than Burn, so Dino buff isn't as high but I'm less reliant on Dino. Easily 60k DPS without any buff just the Pyroclasm. I'm also sacrificing Weakspot so showcase on dummy is lower.
https://steamcommunity.com/sharedfiles/filedetails/?id=3358140119