If I'm understanding your question, what you want is basically impossible in Premiere Pro alone. You probably need another app as well (like Audition).
I need more specifics... but what I'm assuming from you question is that you have a finished tutorial, correct? One complete exported file that includes video and audio... and you're trying to bring that into Premiere Pro to make the edits you mention. Does the audio include any voiceover or SFX as well as music, or does it only include music? If it's one of those tutorials that is only music under just the visual of a mouse clicking on the screen, you may be able to pull this off. If there is any voice or SFX as well, you can't do it in Premiere Pro alone.
If it's music and video only (no voice or sound effects):
Drag the tutorial clip into your timeline. Then, right click on the video part and choose Unlink from the menu. This separates the video from the audio so that they can be tweaked independently. Then, you should be able to do what you want: select the video clip only and change time/duration. It won't affect the audio, and you can do what you desire: loop the music underneath. This works because the music doesn't have to be synced to the video in any way. Any part of the music can play under any part of the video and it will still work.
If your audio has voiceover (explaining your topic) or sound effects synced to the video, this is much harder and perhaps not possible. First, do you have an original Premiere Pro project file for the tutorial, or can you get it from wherever? That would be the obvious way. All the audio and video clips could be worked on separately. If all you have is the final export, with music/voice/SFX baked in, the above solution won't work. Because when you unlink and change the speed of the video, the voice and sound effects will no longer be synced correctly to the video.
In that case, what you need is a way to separate the voice from the music in your audio track. So that the voice could be slowed down/sped up with the video (although that may end up sounding funny). Premiere Pro does not do this. I think Audition has some tools that can do this... perfect results not guaranteed but it might (?) be close enough.
If you have Audition, I suggest posting in that forum: How can I separate the voice from the music in my track? Better yet, google it first and see what you find. I'm not an Audition expert. If it's possible, then you can edit the audio in Audition and then bring the separate voice, music, and video into Premiere Pro and do what you need.
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