[SOLVED] Capturing/recording gameplay

I've never done this before so I'm asking for help. How would I go about capturing gameplay so that I can upload it to youtube or similar? I'd like to show off my movement and balance settings.

To record video from xonotic you have two options as far as the codec goes and thats AVI or OGV to use the ogv option which is enabled by default cl_capturevideo_ogg 1 you will have to tweak the ogg settings if you use ogv for recording for AVI uncompressed recording which will use about 2.5GB a for a one minute video at 1280X800 at 30 FPS its cl_capturevideo_ogg 0 but the AVI is worth it IMO and can be converted easily to a h.264 AVC file, youtube prefers h.264 and AVC is very good. the audio codec used doesn't really matter ACC MP3 PCM w/e.
What I do and have found works well is recording video from a xonotic demo file its better then recording while playing a game just tick the box under demos that automatically records demos while playing then and go back and play the demo and use cl_capturevideo 1 to record and cl_capturevideo 0 to stop and remember to take off any thing you don't want to show in the video like say if you play with shownetgraph fps qu speed etc what ever you have up will be recorded. The video will be saved in the hidden .xonotic/data/video under linux not sure where on the other systems.

will you be my valentine?

EDIT
I typed the command in wrong.