Mickstix

If your sure your throttle "trim" and end point adjustments(on the transmitter) are set right, then from looking at the video, loosen the collar on the right, and slide it closer to the carb, compressing that spring, then tighten it back up.. If you load that spring enough it'll return the carb to closed.. Also, if you've completely loosened the idle screw, it could of come out of it's groove, in the carb throttle body.. There's a groove the idle screw rides in to adjust it.. With all the linkage removed, that throttle arm should rotate back and forth freely, from wide open to idle stop.. If the idle screw gets out of it's groove that arm wont rotate freely, and also not control the idle properly.. You can fully remove the lsn screw and take that whole assembly out of the carb.. There is a sping inside that pushes the throttle body away from the back wall, so it doesnt bind up.. Make sure all that stuff is good to go and you should be in business! Good luck!
NOTE:If you do decide to remove the LSN and throttle housing, make sure and note how many turns "out", the LSN screw is currently..So when ya put it back together, you'll be able to return it to the same tuning..