PlayAlong titles include professionally recorded backing tracks, built into the Noteflight viewer. After purchasing, you will be able to play along with the backing tracks by accessing your purchase on My Account > Order History. (PlayAlong backing tracks cannot be downloaded for offline use.)
PlayAlong titles are also included within PASS.
You are able to mute the demo track by clicking into the Playback settings button above the music:
Then mute the instrument track: