a10-6800K din processor ko and wala naman akong problema dati sa mga playback ng videos (mga lampas 6 months bago ako bumili ng video card). i assume you are using the built in video right? nainstall mo ba ang drivers ng amd? kasi sabi mo nag install ka ng catalyst but if memory serves right, if you installed the mobo AMD drivers kasama na yun dun dapat (in my case, gigabyte mobo ko and kasama na siya)
have you tried other videos? how about other players (i.e. kmplayer, potplayer). pag ganun parin, ano refresh rate ng monitor mo? baka naman mga tipong 16ms or higher ang refresh rate niyan and the video is encoded with very fast bitrate and hindi kaya ng monitor