can you take a headphone out of your interface into your ot for sampling?
Or, if you set the ‘dir’ settings on the ot mixer to max, and hook your computer speakers to the output of the ot, you can live sample and still hear what you are doing.
Or, how about using audacity on your computer to live record the YouTube and trim it, then upload to the ot via USB? (Oooh, iMac, sorry, I don’t think you have audacity available.)
Or, use one of the YouTube downloaded web sites to convert the audio to MP3 and download it to your computer as a file and slice and upload to the ot via USB.