Well I've gotten mixed reviews you guys say it could be an exhaust leak but I suspect it's inside the front head. I've gotten a lot of people saying it's the HLA's. I've taken the engine out of the bike and it's inspecting the front valves and rocker arms trying to determine how to tell if I need to replace them.
It's tough to diagnose from a video. Both problems, exhaust leak or collapsed lifter/valve problem could coincide with a change in exhaust note, or cause that change. I wouldn't have touched a bolt until checking the possible leak areas and listening with a stethoscope.
I think if it's a lifter, it should be on one of the exhaust valves (because of the sound in the pipes). But check them all. Remove and bleed the lifters, get them full of oil, then see if one is a lot easier to compress than the others. It may be obvious and the bad lifter is just limp. Compare the height of all the lifters, bad one can be shorter if damaged internally. A good lifter will be very tough to compress by hand (probably will need a tool), the bad one will be easy. You can place a rocker on top and use that to press down.
Rockers - A rocker mated to the bad lifter could have some unique wear patterns compared to the others, from tapping the valve stem or the lifter pocket on the rocker due to excess clearance.
Exhaust leak - Should see where gases have been going past the gasket, a burned area or soot.