We have seen that force users frequently gesture while invoking their force powers;
- Young Obi-Wan makes pushing motions when knocking over droids
- Old Obi-Wan make a dismissive gesture to accompany "these aren't the droids you're looking for"
- Vader makes a pinching gesture while playfully crushing people's throats
- Young Vader waggles his fingers while guiding his fruit into Padame's mouth.
Now let's consider the clip in question, with the cool stuff beginning around 50s in:
Vader ruins people's day
To start, he swats a few blaster bolts aside with his light-bat, sending them back toward the rebels. At about 1:05 he gestures at one of the soldiers and with a twisting crushing gesture force-slams him into the ceiling. He maintains his closed fist - and the guy stays on the ceiling - until about 1:10 when he releases his "grip" - at exactly which point ceiling-guy starts to fall - in order to stretch out and deflect an incoming blaster shot with that hand. He then makes a reaching gesture, disarms whoever's left, and proceeds to, in the vernacular, "whale" upon them.
Back to the gesture in question, the editing and framing in the scene make it clear that the intention is to show the closed fist gesture is absolutely connected to the fate of ceiling-guy, and has nothing to do with "catching" blaster bolts.