The final, written file, yes. MP4 and MOV is a very “lossy” format that uses a great deal of compression.
Just to clear the terminology:
MP4 and MOV are not the 'formats' but containers. Inside them you can code audio&video in any of many 'formats' (or codecs), either lossy or losseless. In Breeze 4K we have h264 as codec, with (unknown but seems pretty high quality) fixed bit-rate, which is the main parameter for size and video quality.
Since 5 minutes of 720p@60fps produces cca 700Mb (I mostly use that mode because of 60fps), in max battery time of 15 minutes, it couldn't be larger than little over 2GB. Since 1080p format has the similar size, it's probably using parameters for higher quality because it has twice lower fps (30). Haven't tried 4k recording since it is not stabilized, but I can bet that the parameters in h264 codec are fixed so that max timed recordings have the similar size (cca 700MB).
However, when that file is open and being written to, as the sensor is dumping data into a memory cache, it can and will approach that 4Gb limit.....at which point the system starts a new file and writes/compresses the previous file and releases the memory that was being used.......until this new one approaches the limit and it happens all over again.
The technology of coding lossy format, like h264, is that it writes full image (so called keyframe) every so (various condition, fixed or variable, in Breeze 4K every 2 seconds). Every frame between 2 keyframes is recorded as a relative difference to the previous frame (highly sofisticated algorithm, in h265 even more), so it is a pretty low data written. Five min. footage has cca 150 keyframes (full size images), and all other 17.850 frames @720p (or 8.850 @1080p) are only the differences.
So the FAT32 and its 4GB limitation is surely NOT the reason why the video is set at 5 min. max. It could be the tax/import/export laws, but as I know that has been set at 15 or 30 minutes, depending on the country.
The only logical reason is that it's for security of not losing the footage.