You don't need a functioning charging system for the bike to start as long as the battery is fully charged. Cranking sounds a little slow but if you ran the battery down a bit cranking before the video that would explain it. Sprag sounds OK but supposedly cranking with a low battery can tear them up. I'd replace the coil with the weak spark. Is it getting fuel? Do you hear the fuel pump run? Try a little starting fluid and if it fires and dies then you know fuel is the problem.