Put the video clip you want as the background on the main track, then put the video clip you want to have in the corner on the track below; it will temporaily overlay the other video, just resize it to your requirements / move its postion to where you want.
More overlay videos can be added on the tracks below if required.
Director Suite 365
AMD FX-8320 3.50 GHz Eight-Core
Samsung SSD 850 EVO 250gb (OS)
Seagate 2TB SATA-III Hybrid 7200RPM Hard Drive (Data)
Toshiba 4TB SATA-III Hard drive (Archive)
24GB Memory
Nvidia GeForce GTX 650 2gb
Microsoft® Windows 10 (64-bit)