I was looking for ways to record video of most my League of Legends games. Going right through different forums and everything until I found a very useful tool. I have tried it a couple times, and if you're computer isn't so high end like mine, you can capture, record and share every moment in your game free of charge! This may not affect your performance.
It's really quite 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. Ensure you contain it running in the backdrop when you're in a game LOL. This may record every single moment that happens. Whenever you replay it, you can scroll around and view everything. There is a slow-motion button, as well as fast forward and pause. The only thing missing is just a rewind button. Google LOLReplay and click the very first link for a download.
2. Download and use a free version of Fraps - This only lets you record 30 seconds at any given time, which means you will have to put them together in a video editor program. I personally use Windows Movie Maker. Whenever you run the replay, Fraps moments that you think are good and deserve the spotlight. You can even keep clicking the record button if you wish to record the complete game. It will then save all 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 generally share with other folks via YouTube, or any other video sharing sites. If you just need to view the replays for personal gain, then this is not needed. I have tested this approach and it works very well if you are a free of charge method. You can even use other recording software such as for example HyperCam, but I have had better success with Fraps. If you don't have Windows Movie Maker, or would rather an alternative solution, Ulead, Honestech and Power Director are similar and won't break the bank. This software does cost a tiny amount. If you wish to stick to a Free method, I strongly suggest using Windows Movie Maker,
Although might also want to check on into VirtualDub, it is just a free editor that lets you cut, reverse, flip, resize, and apply other special effects to .avi files. It's perfect for clearing up videos before entering them into the timeline.