The Gator Roll is an extremely effective takedown if completed correctly. From the collar tie and inside bicep tie position, move your head in close to your opponent's shoulder whilst pulling on the collar tie bringing their head into your shoulder. Once in this position you can slightly step back and snap their head down using your 'collar tie hand'. Then place this same arm under your opponent's neck and grab their opposite upper arm, pulling their bicep across their face. You now have a good head and arm position. Lastly you step away from their trapped arm causing them to widen their stance, before dynamically rolling to your oppostie side taking them with you, using your free hand to assist the roll via their leg if necessary. This will leave you in a good side control or north-south position.
A great example of this being used in a fight, is 4:47 minutes into the Strength & Honour - Nestor Costa Vs Kyle Davies bout.