You can record directly from your computer's soundcard into Traktor - ideal for grabbing samples from YouTube.

With this mapping you can capture, edit and save a sample using your computer's keyboard alone. Very useful for editing on the move.

Controls include:

Start/stop mix recorder
Load recording to Deck A/B
Start/stop loop recorder
Load loop recording to slot
Play and scrub
Loop in / Loop Out
Set hotcues
Load/Unload Decks
Load/Unload Slots
Save/Load remix set
Set sample to Track/One-shot/Loop
Browse list/tree

Settings information and a list of keyboard commands included in the download.

I'm using a Toshiba Satellite laptop. Keyboards vary so this mapping might not be ideal for everyone. If you have any issues, you can post in the comments below.