How can I play a video with alpha in WidgetBP?

I bought a MenuSystemPro plugin and I’m trying to replace game logo with an animated game logo. For now, I managed to replace it with a Material that is set to UI interface and has two video textures, one for Final color and the other for opacity. I set the image component in the UI widget to that material and I played it at the appropriate time using play source in the graph tab. The video plays, but the transparency doesn’t work and I’m not sure what is causing it.