Whichever your browser can encode — WebM in Chrome, Edge, and Firefox, MP4 in Safari. Pick the container you want under Output format; unsupported ones are disabled.
No. All compression happens entirely in your browser using the MediaRecorder API.
The video plays in real-time during compression. A 60-second video takes about 60 seconds to compress.
Files up to 500 MB are supported. Very large or high-resolution videos may be slow depending on your device.