When you work with « seconds » you can put the shots wherever you want on the timeline. It is the same with Bars & Beats but we added a feature to « magnetize » the start of the shot on the beat for helping you following the rhythm of the music.
When you desire a shot to be exactly on the beat simply press the shift key (⇧) then slide the start of the shot to the selected beat. The shot will be automatically magnetized to the beats positions. If you don't hold the shift key you can place wherever you want the shot as usual.
Reminder: You can move on the timeline from one beat to another by pressing Shift (⇧) + ← or →, the playhead goes to previous or next beat automatically.