A screen recording can show passwords, messages and customer data. Recording and editing it in your own browser means none of that ever travels anywhere.
Make a video small enough to send, convert it to MP4, WebM or MOV, cut out the part you need, fix one that is sideways or remove the sound. You can also record your screen, record yourself on camera, turn a short clip into a looping GIF or save a single frame as a picture. To get just the sound, use Video to MP3.
Compressing, converting and rotating run inside your browser, so they are slower than an app: a small clip takes about as long as it plays, and an HD one several times that. The first time you use one, the video engine (about 30 MB) is downloaded once and then kept on your device. Recordings are held in memory until you save them, and screen recording needs a computer.
The engine is ffmpeg compiled to WebAssembly (the ffmpeg.wasm project, version 0.12.10), including the x264 encoder. FFmpeg and x264 are free software released under the GNU General Public License. The source code is available from ffmpeg.org, videolan.org and github.com/ffmpegwasm/ffmpeg.wasm.