Some people do have access to MOG files which have all the tracks separated. These people usually work in studios and have access to such files, or pay money, or have the talent to actually create multi-channel and multi-instrument recordings.
There are a couple of good ways to get a backing track. If you just want something to jam to for lead composition or otherwise, then just convert the YouTube feed into mp3 at http://www.youtube-mp3.org/ . I use this all the time for rhythm practice and general jamming. After conversion to mp3, I import into the DAW - Scarlett 18i and Presonus Studio One.
For composition ideas and creating 'mock-up' tunes, I use Band-In-A-Box. This allows me to take a rhythm that closely matches the target rhythm for lyrics composed. From BIAB, I remove the instruments I do not want (rhythm and lead guitar, maybe keyboards), then export that into my DAW setup via WAV file.
For cover material, or practicing new cover songs, I go to http://www.karaoke-version.com/ and get the karaoke version of the cover and remove the guitar part. In that web site, you are able to customize the track, so you essentially get a true backing track of a popular song.
Also, for general past time and jamming, I use Jam Player on the iPad plugged into a Line 6 Amplifi 150. Line 6 finally got most of the bugs worked out, so awesome tool. Also plugged into the same Amplifi is a Trio, which is an awesome tool for jamming.
Finally, for traveling and just to have a portable drum machine, I take an electric guitar, full powered iRig setup, iPad, short cables and combine all that with a BeatBuddy and Looper. Besides the guitar itself, all of this packs into a small size and is great for traveling.