Can we add WebM support?

[trankhacvinh]

I need to optimize WebM file but Dinky is not recognize it

[heyderekj]

@trankhacvinh I created a new issue for this. Thanks for suggesting this!
I assume WebM to MP4 is good? Or you expecting WebM to WebM?

[heyderekj]

@trankhacvinh Dinky should now recognize WebM files and will optimize them into MP4, etc. (no WebM to WebM).
All of this is in release 2.9.1 (should be able to just check for updates in menu bar)