Videos are loaded from a self-hosted webservice over http or https.
While everything works fine in Android, in iOS we have some issues:
This specific version of Wikitude SDK 5.3, that supports iOS 10, had some issues regarding VideoDrawables. Therefore, I would strongly recommend that you update to another version, even 5.3.1 if you do not wish to go with 6, and test with that.
I'm using iOS Javscript API 5.3
Could you please tell me which SDK version you are testing with?