I was searching for approaches to record video of most my League of Legends games. Going through different forums and everything until I discovered a really useful tool. I've used it a few times, and if you're computer isn't so powerful like mine, you can capture, record and share every moment in your game free of charge! This will not affect your performance.
It is really really simple, you basically should do two things.
1. Download and install the League of Legends replays - This runs in the backgrounds and records/saves everything. Be sure you have it running in the backdrop when you're in a game LOL. This will record each moment that happens. When you replay it, you can scroll around and view everything. There is a slow-motion button, in addition to fast forward and pause. The only thing missing is really a rewind button. Google LOLReplay and click the initial link for a download.
2. Download and use a free version of Fraps - This only enables you to record 30 seconds at the same time, which means you will have to put them together in a video editor program. I take advantage of Windows Movie Maker. When you run the replay, Fraps moments that you believe are good and deserve the spotlight. You can even keep clicking the record button if you wish to record the entire game. It will likely then save most of the files in your Fraps/Movies folder. Open them in the Windows Movie Maker and edit it how you prefer. Google fraps download for the download.
This is only needed if you wish to talk about with other people via YouTube, or any other video sharing sites. In the event that you just need to view the replays for private gain, then this isn't needed. I've tested this technique and it works quite nicely to be a free method. You can even use other recording software such as HyperCam, but I have had better success with Fraps. In the event that you don't have Windows Movie Maker, or would like an alternative, Ulead, Honestech and Power Director are similar and won't break the bank. This software does cost a tiny amount. So if you wish to stick to a Free method, I strongly suggest using Windows Movie Maker,
Although may also want to check on into VirtualDub, it is really a free editor that enables you to cut, reverse, flip, resize, and apply other special effects to .avi files. It is perfect for clearing up videos before entering them to the timeline.