RE:
I think as long as you hold the contraction you should be fine. On a side note I would not take out my weights, maybe use moderate to light poundage and don't go over 12 lbs total
Some excellent videos with great glute exercises are:
Cathe
Muscle Endurance
Power Hour
MIS (don't go heavy on this one)
Margaret Richard (just about anything, this is the queen of tough floorwork that includes the bridge work)
Karen Voight
Total Body Pilates w/ ring
Great Weighted Workout (floorwork section)
Firm Vol. 1 w/ Susan Harris (the floorwork is grueling)
Kickboxing also works your glute really well and is a great cardio workout too.
You might want to try some pilates as well. The only one that I like is the Winsor Pilates Buns & thighs w/ band.
HTH
Kim