Stop and rewind the song in 5 seconds intervals using either the mouse or better yet using a three button USB floor pedal.

You can use a USB pedal on Youtube videos and other media but Chordify has no way to back up from the stop point. It either goes right back to the beginning of the song or starts playing again from the point that you stopped the song at,  If Chordify had the feature to stop a song then back up or go foward to any point of a song that you are trying to learn, it would be much easier to use.  I install a 3 button USB floor pedal that will let me stop a Youtube song and back up and play any part of a song that I am working on learning.  I can do this with a $40 dollar USB pedal using my foot and never have to have my hands leave the guitar.

Just a thought,
Best Regards,
Mark R