Controller disconnecting and 3rd party controller not supported

When I turn on my Gamecube it flickers oftenly like the cable is loose, i also have to sometimes plug my controller out and back in to make it work again and I can only use my official nintendo GC controller since my GameStop GC Controller doesn't work on this one. The GameStop GC Controller works on my other Gamecube, when I start a game the controller gets disconnected every 30 seconds and I have to plug it back in and out to make the controller work again for another 30 seconds.

Here is the video and a picture for more information: https://www.dropbox.com/sh/tozu2q9crye48...