Question 1

Do my videos get uploaded?

Accepted Answer

Never. The video engine downloads to your browser once (about 31 MB, then cached) and every trim, compress and convert runs on your own device — there is no server to upload to.

Question 2

How big a video can these handle?

Accepted Answer

The engine works in memory: roughly 1 GB of source video on a desktop browser and around 300 MB on mobile. Trims, mutes and remuxes are the cheapest jobs; full re-encodes are the heaviest.

Question 3

Which tools are instant?

Accepted Answer

Anything that copies streams instead of re-encoding: trimming (lossless mode), muting, merging clips that share a codec, and MOV/MKV → MP4 conversions. Frame extraction skips the engine entirely.