I do not understand why you changed the code in the plug, all the time could
download and without problem.
For a moment, any link can download without problem and at another time - not work correctly.
So, how do you want to fix random errors occurring?
Without testing - links will not be useful.
For comparison - Addon VkOpt without any problems show URL direct-https-links
Code:
HTTP (csXXXX)
HTTPS (csXXX + pp.vk.me)
Previously I sent log awaiting that whatever you see. But You not see anything.
So sometimes it is better to post additional minor information that I see in the logs and where you can not see FULL LOG!
Please Increase Size Log and 500MB -1000 MB and download and download.
Open all the "parts" of logs in the editor and export information:
Search for information, for example. Failed, Error, Plugin Defect others info as I gave earlier ...