Code:
https://www.youtube.com/about/copyright/fair-use/
You are allowed to modify other videos and make compilations under the fair use act, but you need to make sure it conveys a new point or feeling. This helped me with a video that earned over $1k before I took it down. Think about the compilation and make it high quality.. If you get a copyright strike you need to respond appropriately to youtube and prove to them you are using it under fair use act. There is no guarantee that they will approve it by make sure the letter is convincing.
Keep in mind that audio files are now in the Content-ID system and is automatically scanned for duplicate content so the artists can get paid for streams. Independent artists upload their tracks to many streaming services at once using digital distribution services like Distrokid, United Masters, CD Baby, Tunecore and more. There is an easy way to see if the audio is in content ID, well atleast songs published on the platforms listed above.
How?
Check to see if the song is uploaded to itunes, spotify or amazon which are major players. If the song is uploaded on those platforms then you need to make sure you modify the audio as well to stay under the radar.
If you need audio files let me know I will help you, I'm a producer. I wouldn't mind doing some studies and modifying different properties of the audio files to see what can and can't fly under youtubes radar..