Well, there are many recording softwares for use in the web, the most popular ones being FRAPS, bandicam, etc. FRAPS is a paid software, so you'll have to pay for it if you pretend to use for future videos, since it leaves a watermark in the top of the video. Also, when you record something, extra computer's resources are in use, so the FPS will drop.
It's simple how to use 'em. Play the game, use any software of your interest, learn the program's shortcuts and options, record your gameplay, with voice or not, and upload them via web.
The new Shadowplay software is due to be released soon by Nvidia. It is supposed to have the lowest performance impact of any recording software. The due date was to be this week, but it has been pushed back, and is now supposed to be out "soon".
Some info below:
ShadowPlay: A Revolution In Game Capture, Coming Soon To GeForce Experience
Capturing footage from your favorite games can reduce frame rates quite considerably at native resolutions, in addition to reducing level and texture load speeds if capturing to the hard drive holding the game. Furthermore, some apps record using uncompressed formats, filling your drive with gigabytes of data.
If you own a GeForce GTX 600 or 700 Series GPU, you’ll soon have a new option for creating high-quality captures, courtesy of an upcoming GeForce Experience module we’re calling ShadowPlay. Completely free to use, ShadowPlay leverages the H.264 encoder built into Kepler graphics cards to record max quality, native resolution gameplay footage that is compressed and encoded on the fly, before being automatically saved as a YouTube-friendly .mp4.
ShadowPlay promises to revolutionize game footage capture by leveraging the high-speed, integrated Kepler encoder that also powers NVIDIA Shield PC game streaming. And because it's a dedicated hardware encoder, you'll be able to capture gameplay footage continuously without tanking your framerate.
In addition to traditional game capture, ShadowPlay users can activate Shadow mode, which continually records and saves the latest action to a user-definable buffer. If you pull off an outrageous mid-air maneuver in Battlefield 3, simply hit a predefined hotkey and your moment of glory is instantly saved to a .mp4, ready for publication on YouTube.
Perfect for the majority of gamers who don’t require a capture of every single second of action, ShadowPlay’s innovative new mode ensures you never again say, “I wish you could have seen that!” With ShadowPlay enabled, every special moment can be captured and quickly shared, demonstrating your pro-gaming skills to your best friends.