The 100 lb weight is equivalent to 445 newtons.
Next, you have to determine the vertical distance from the center of the motor shaft to what we call the "center of gravity" of the TV set (This a point where if you placed the TV on a single support it would be balanced and not tip any direction). This might be a point 1/2 of the distance from the top to the bottom of the set but it probably is not: because, the internal electronics may well be in the bottom of the set and this will move that point closer to the bottom of the TV. If you want to be safe you can simply use the distance from the shaft centerline to the bottom of the TV.
The minimum N-M torque that will lift the TV to a full horizontal postion is then 445 x the distance from the shaft centerline to the balance point or bottom (in meters). Once this is determined, then you should multiply that value by a minimum of 4 or by the amount stated by the motor supplier to provide an appropriate safety factor.
With all of this said, you need to realize there are a number of operating and mounting components as well as ceiling reinforcements that need to properly addressed in any installation like this, particularly in one that is going to be a falling hazard to anyone passing below it.