Creating a split screen effect
FFmpeg, a command line tool, can accomplish this, via this command.

ffmpeg -i left -i right -lavfi [0:v][1:v]hstack -pix_fmt yuv420p -an combinedvideo.mp4


Replace left with filename of video to be positioned left. Same with right.

ffmpeg (32bit static build) can be downloaded from here. The ffmpeg.exe is in the bin folder of the archive.