Right well there is a hacker on the same server as you and you want to record him and post it on youtube or w/e.
First thing is go to spectators. Then go to the player that is hacking.
Open console and type "record NAME" (without the quotes and whatever you want to call it instead on NAME)
This will record a demo file (.dem) and is only watchable within source. You can't upload to a site just yet.
In order to make this demo into a video file so you can watch it on WMP (Windows Media Player) or whatever you use, you need to load your demo.
To do this you open source and type in the console playdemo NAME. This will load the demo. Once its loaded, open console and type "demoui" (without the quotes)
This will bring up a box with some controls allowing us to fast forward the demo, slow it down and jump to parts.
Right jump / fast forward to the bit you want to put into a video. Pause the demo on the demoui. Open the console and type "startnovie NAME AVI" without the quotes. IMPORTANT - if it doesnt show a separate box showing the different codecs Then you need to press escape and type "endmovie"
Retry trying to record the AVI file until it brings up the box showing the codecs. Once its done that choose any codec apart from uncompressed. You will be creating an avi file between 200mb and 6gb. You WILL need to use sony vegas or an alternative to compress it down to an accessable size.
Once you have set it up so its converting to video, resume the demo on the demoui and close it (click the X in the corner of the demoui).
Once you have done that your game will go EXTREMELY laggy(starting the video recording not closing the demoui). Im talking about like 3 fps. Also there will be no sound. DONT WORRY your video will come out fine.
Once you have got past the bit you wanted to record, open console and enter "endmovie" This will stop the movie recording.
Once you have done that the avi file will have been placed in you cstrike folder i think ( either that or the folder above it).
You need to open your video editing software and import the video you just made. Then for youtube you need to make it into like 640 x 480 resolution and mp4 for best quality. (Thats what youtube suggests but ive never found youtube to give good quality for anything)
Thats about it...any questions just post after and i'll answer asap.
Quite a long post but its pretty detailed

Its more or less exactly what i do.
Btw sorry for my spelling im doing this at school while my teacher isnt looking.