pb to insert a personnal logo

Hello,
i purchase the plugin,
insert the licence key, and that’s work, the logo “contus video gallery free” erase from the plugin.

But now, i try to insert a personnal logo, but when i insert a file, but the the screen of a video are blank.
in fact on the right of the button to upload the file, i have “no file selected” and on the right side i have the name of the file that i select.

https://www.ads-software.com/plugins/gallery-video/