I was wondering if you could provide more information about your issue, for example:
How long is it taking to download videos to your player?
What is the collect interval set to for your player?
What is the total size of the videos that need to be downloaded to the player?
Do you have XMR configured on your Linux player?
I have been testing with my Xibo for Linux player (1.8 R6 108, running on Ubuntu 18.04 and also on Ubuntu 20.04) and so far I have not seen any delays downloading the video files. For example, I created a layout containing 2 videos, the total size was approximately 150MB in total. The files were downloaded and displaying within a few minutes.