In some country, YouTube is blocked...

So,Why does slides not support the use of local files, at least this as an option?

Or can support other ways to read video files, such as reading files from other video platforms (such as YouPHPTube), or may be from a static site...

Please support this !  Because , This way of slides now actually makes it impossible for users(Site builders) in these countries to use the presentation feature. And, Since relying on the client to download during playback, this actually means that browsers in these countries are not able to use this feature.

By the way,In these country, Google Drive is usually also blocked.