[daeken]

It is actually slightly more complicated. The existing effects work in GLSL and are just transforming single frames of video. For that effect to work, you need the previous buffer states; this means that seeking will cause the image to be different, and you need to feed the previous render state back as a texture.

[ricardobeat]

Just draw the frames to a 2D canvas, without clearing it, then back to the background buffer.

[daeken]

You still need to remove the green-screen. This either means an expensive process on the CPU side, or pushing the frame to the GPU to remove it with a shader and then using RTT and rendering that or reading the framebuffer and drawing that to a canvas. Note, it's really not difficult to do this, it's just slightly more complex than the other effects, is all.

[ricardobeat]

The demo is already removing the green-screen, I don't think that's the most expensive part.

[daeken]

Well no, the demo is removing the green screen but only in the shaders. As I said, this really isn't a big deal, but it does add complexity.