Fix basic video effect

[lukasf]

The namespace change broke the video effect.

We could take this chance to also rename the video effect. Perhaps rename to HardwareVideoEffect?
I do not want to keep the old namespace for it, so we have a breaking change anyways.

[brabebhin]

Out of curiosity, what Windows version do you use?
The video effect works periodically for me now, still getting the "window destroyed" error, it sometimes randomly fails activation (similar to other bugs i've encountered with it).

I am still pretty sure this has nothing to do with our library and only MF bugs.

[lukasf]

Huh really? For me it is super stable. I am on Windows 10 21H2. Do errors occur also in the sample app for you? I know that there are problems when using effects with MediaPlaybackList. But without that, I have never seen issues.

[brabebhin]

In hindsight, we should probably use a const for the activatable class ID when registering the effect.

The issue occurs with the samples on my laptop but does not occur on my PC. I installed some special nVidia drivers on my laptop (was using the GPU for some very nasty compute stuff) which is the only significant difference between you, my laptop and my PC. I would not pay too much attention to this.

We could also extract this into a different library. It would indeed make more sense than keeping it the main project.