Can't place mutiple videos on timeline???

You need to pay attention to source & track targeting ...

The blue blocks on the left are "Source" targets, for bringing media from the Source monitor. If say you have a blue box (on) for A1's audio track but no blue box on the video tracks, you only get the audio not the video. The reverse is also true.

And for quickly adding things from effects and libraries and such using keyboard shorts especially, using  track targets (the right blue blocks) target where incoming assets will "land".

Neil