@Javierbspp I hope the problem is now fixed. if it is still not there, it means the video is only available in Particular format. If your problem is solved, then please let me know?
@Javierbspp Go to the video > Tap on Download.
Now, you will see two options. One is for video quality and other one is for size.
Tap on Quality and select the desired format. For more, see the below screenshot.
@Javierbspp Btw, if you have any suggestion regarding this app development, then you can drop a mail to the developer. You can get the official website link by clicking on the developer name on my website.