White screen while loading video with GL Video

Try the regular video library for processing. Also it would be helpful to know your setup, like are you using latest RaspberryPI OS. There’s no official support for the PI since Gottfreid Haider left. But I’ve been successfully running PiCrate on both RaspberryPI OS 32 bit and Manjaro ARM 64 bit and a development version of processing on Manjaro ARM Video Capture on RaspberryPI4 with Manjaro Arm. Be aware you need to follow me and install Sam Pottingers version rather than official alpha release (which has a spanner in works to prevent use on PI).