This happens to me to, I record on a Acer laptop.. Not good for this kind of stuff.. But yes it's your computer not the cap card, or even your editing software.. Your computer can't handle it all, and it lags the clips for a few seconds, then speeds up to catch up.. Try and record for an hour, two max, stop recording, save what you recorded, and turn the comp off for a bit let it cool down. After a while start it all back up n record, or just edit what you have, it's a pain but it's the only way unless you wanna upgrade to a bigger processer or new computer. If you keep the clips that were lagging/fast forwarding, they will be like that when you upload to youtube..