i think he still has tension on the bars. Looks like he removed the front brakes and undid the upper balljoint and it came down. Otherwise i am not sure why he has the scissor jack under it.

If the torsion bars are still under tension, make sure you have jackstands under the frame of the car first. Then slide under and back off the adjustment bolt for the torsion bars until they are loose. Then you will be able to bring the lower control arm up enough to reinstall the balljoint.