yes indeed: but if the video source is at 25 Frames per second, as most YouTube and Sendvid clips are, the VLC slowed-to-halfspeed, 12.5 FPS version is significantly juddery.
The clips I'm posting here are based on PAL interlaced 50 fields-per-second video: I'm de-interlacing this to 50 frames-per second video, then slowing it to halfspeed: 25 frames-per-seond. The results are significantly smoother than just slowing down a 25 frames-per-second source.
I'll try and make up some examples GIFs to demonstrate the difference.
I switched to a Linux laptop a while ago, so all those mac-specific video editing tools I used to de-interlace and slow down clips are no longer at my fingertips. But I've finally worked out how to do the same job with linux & cross-platform software (audacity, handbrake and MKVToolnix if you're interested).
So Here's the first new half-speed routine in a year and a half: Legs & Co. dancing to the Beach Boys "Lady Linda".