Demo: https://iamdevonbutler.github.io/joinyoutubeclips

Basic:

?videoId=startTime-endTime

Multiple videos:

?felDULf1voY&AV1jKBrw0ck

Multiple segments:

?felDULf1voY=0-10,100-200

Autoplay on start:

#play

Segment time

To create a segment, the time values can be in seconds (90) and/or hh:mm:ss (1:30)