How to determine force directions in torque problems

[oneplusone]

Hello,

Is there a rule to figure out what direction a force must be applied in a torque problem?
Here's a specific example with a question:

In this video, how did he get the direction of F1 and F2? Like how did he know it was pointing upwards or downwards?

 

[PhanthomJay]

After awhile, you'll get a good sense a of the direction of the unknown forces in many problems, but otherwise, you can assume a direction. Then when you sum torques about a point = 0, if the force comes out negative, you assumed the wrong direction.