Congratulations ! Yes I think valve adjustment is in your future. It sounds a bit like a thrashing machine but some of it could just be the video. Make sure you check the oil to the rocker shaft. That could be some of the noise. These often plugged with sludge from old oil. They even used to sell after market oiling kits to bypass clogged passages. At least you now have a runner to play with, much more fun.

"I wonder if God created man because he was disappointed in the monkey?" Mark Twain