Don't record while playing. Save the replays of the matches you want recorded. Then use fraps to record the replays. It's 60 fps so make sure you specify that in fraps. The files you record will likly be more than 4Gb, and be broken into smaller files by fraps, so use some editing software to combine them into one video, and export uncompressed or losslessly. Then use an H.264 encoder to make the final encode and compress to a more reasonable file size.