Lossless means that the data is compressed on a bit-level. Has nothing todo with encoding. Similar to WinRAR and ZIP, it probably uses a compression algorithm specific to cloudflare storage to serve the video faster?
You can have lossless compressors tailor-made for specific applications who will typically achieve a better compression ratio than the "generic" compression algorithms WinRAR, ZIP and friends use.
For instance try zip'ing a WAV file and compare it to the same file encoded in FLAC. Typically FLAC will achieve better compression while still being lossless.
There are lossless video codecs, like VC-2 for instance. It's not very common in the consumer world however because people generally don't want to stream or store high definition video with a single digit compression factor (that single digit being generally around 2).
For instance try zip'ing a WAV file and compare it to the same file encoded in FLAC. Typically FLAC will achieve better compression while still being lossless.
There are lossless video codecs, like VC-2 for instance. It's not very common in the consumer world however because people generally don't want to stream or store high definition video with a single digit compression factor (that single digit being generally around 2).