64mb RAM, and a 400mhz CPU, honestly? My pc from 15 years ago had more RAM than that, and it had a 333mhz processor, and a 6 GB hard drive.
I'd say the bare minimum is 500 mhz processor, 128mb ram, and some kind of graphics hardware with DX9. Even with that you're pushing it. The event engine bogs down HARD on slower cpus with anything remotely complex. Anything with shaders will also kill framerates on older gpus.
Anything made with Construct needs some kind of graphics card to run at acceptable frame rates. I just don't think a 15 year old pc would cut it.
2. How can you import video into the runtime? You can't without a special plugin or python. You can let the user load music, but what do layouts have to do with that? You can just simulate different "layouts" with proper design, all on a single layout.