Line 64 in https://github.com/ezsystems/ezplatform-http-cache/blob/master/docs/varnish/vcl/varnish4.vcl seems also matching content/download urls which should vary by user-hash.
eg. /content/download/29877/video/test.mp4

// Do a standard lookup on assets (these don't vary by user context hash)
// Note that file extension list below is not extensive, so consider completing it to fit your needs.
if (req.url ~ "\.(css|js|gif|jpe?g|bmp|png|tiff?|ico|img|tga|wmf|svg|swf|ico|mp3|mp4|m4a|ogg|mov|avi|wmv|zip|gz|pdf|ttf|eot|wof)$")