I will request the feature to download the specific song and use it on KaraokeTabs offline in case you dont have internet... It would be a great feature for a game like this one. I hope I helped ;)
Perhaps I can add the ability to open any video file. You would need to have the video already downloaded on your PC (using another app for doing things like that). So if you have a video on your HDD (offline) you can open file with KaraokeTabs. Then you you still open the tabs and play them in sync.
Thanks for the great suggestion @The_Coder2010 !