If someone is still using Enscape Version 2.9 and 3.2 then they can use this trick to create a transparent video texture .
This trick will not work in Enscape Version 3.0/3.1/3.3/3.4/3.5p , I have created a separate thread in Bug | Error Reports section so that this can be fixed and implemented in upcoming release.
Unintended Video Texture feature in ENS V2.9/3.2 versus in ENS V3.0/3.1/3.3/3.4/3.5p
Fell free to ask if you have any question or query.
This could be really awesome if it gets soon included in the official release. I tried something similar, but had to give up.
We’ve been asking for this since the day video textures were added into the program! @Demian_Gutberlet can you tell the devs to revert back to whatever allows this to happen so a feature we’ve been asking for years now will get added. Thanks!
Edit: It is almost two years to the day (11/6/2020) that video textures were added but they still don’t have native alpha channels.
Haha is this the reversed ‘it’s not a feature, its a bug’? 
But it’s something that this wish has not been added for so long while it actually was possible all along. 
Alpha channels in videos are not particuarly well supported anywhere , it’s not an enscape only thing. I don’t think enscape supports any of the codecs that can technically support it either, such as prores 444 or webm.
It would be good to know exactly what codecs are supported by enscape/The help documents only list the containers , but not the codecs.
@adam_fairclough I will be honest, I am not knowledgeable when it comes to the coding required to make Enscape tick. All I really care about is the ability to create vertical water and fire features that aren’t static or require post processing. Since Enscape hasn’t indicated they are working on particle effects like Lumion or Twinmotion, the next best thing is transparent video textures. Even if it was a error that caused the above example, it created a output I am looking for. So I hope it or something similar gets added back in.