On multiple machines (Windows 7-10), if I click on an MP4 or other media file, I have the option of checking the box to save the file without asking in the future. With .mkv files, the checkbox isn't there, so every time I have to go through the process of changing the default (play) action to save the file. I've checked preferences and there's no way to add mkv files to the default actions. I deleted the handlers... file to reset and start over, but same behavior...it wants to play the file, with no option to quit asking and just save it. On these same machines, I can do the same download process with any other browser such as Opera, and it just saves the file as I've instructed it to do in preferences. So why the different (and long-term consistent) and annoying behavior with firefox? MP4, AVI, fine, but MKV?? No option, and it's not as if it's a new file type or new behavior. I suppose one could say "what's the big deal, just change it when it asks?", but it seems like nonsensical and pointless behavior, which has continued for a long time, with other browsers able to deal with it properly. At the very least, how about a way to add file extensions manually to the list of actions in the options? Please don't blame the web server for "not sending the proper information", as I've seen in some non-solution posts; the .mkv extension should tell enough, and it's over many servers. I looked in the registry to see if perchance I could patch it in there, but couldn't find entries, so I assume it's all in the handlers file.