The video is crappy and I'm uploading it only for the sound! Gotta a loud thumping noise that I can't figure out... (It's best to just listen and not watch.)

Thought it was the chain but am not sure now. Have tightened and loosened according to manual but the noise continues. Sound comes from directly under the gas tank and I can feel the vibration from it in the gear pedal. It is loudest when I slow down but do not downshift, then try to speed up again. Any suggestions?

It's best heard at minutes 4:47, 4:58, 5:00-5:03, 6:13, 6:19, 7:19-7:22

Please remember it's best to not watch but just listen. :) (less info)