MOV file with alpha channel transparency

Downloaded MOV files with alpha channel transparency and my QuickTime would not open them. "The document could not be opened. File is not compatible with QuickTime player. I think it runs this problem with all MOV files with Alpha channel. I started having this problem after getting my new 2019 Macbook Pro. I try it on the old Macbook pro and it converts files ok. I might have had some codecs installed on the old one. But after one day research i could not find any installable codecs that MacOs Catalina would allow to install. I am really frustrated. Please help.

Hi! Since Apple no longer supports «QuickTime PNG RGB+Alpha» format, Catalonia dosn’t see the files in this format. All author must update their items changing format to «QuickTime Apple ProRes 4444 RGB+Alpha» format. If the author updated the item, download it again. If not, contact to the author and ask him to update the item. Or you can render needful files from old to new format on your old MAC