Minimal warning + hints for too-large video/image files. Possibly could resize/compress in-browser but there's memory pressure issue for too-large files, especially on mobile browsers. Will revisit later. The copy is probably too technical.
Notes:
- It's actually KiB, disguised as KB https://ux.stackexchange.com/questions/13815/files-size-units-kib-vs-kb-vs-kb
- New dimension suggestion is based on scaling factor √matrixLimit÷matrix where matrix = number of pixels (width × height)