Problem 1: i agree this is an annoyance, but there is nothing VDH can do to make those videos play on Firefox 57.
Problem 2: tried all those links, they all either required subscription (and i'm not going to do that), not work at all, or in one case use the visitor's CPU to mine crypto-currency in background :(
Problem 3: they all worked for me :(
Let's focus on the one from dailymotion:
http://www.dailymotion.com/video/x32horo .
- Which variant did you pick ?
- Are you sure you wait long enough ? when you download the video, you first get a file named "- video - Dailymotion.mp4" (yes the naming must be fixed and it will be) which is empty, and a file "- video - Dailymotion.mp4.part" that is increasing during the download. When the download is over, file "- video - Dailymotion.mp4.part" is renamed to "- video - Dailymotion.mp4". At least, this is how it is supposed to work and does in my case.
- In the 1/10 case where you get a non empty file, can you post it on a site like
expirebox.com so i can verify if it is corrupted ?