When you start recording a video and the camera stops after 30 minutes, it is probably not due to a max capacity of your SD card or a malfunction. Some manufacturers prevent their cameras from exceeding 30 minutes (technically 29 minutes and 59 seconds) for a single video file. If you are thinking this is a safety measure to prevent overheating or memory issues, it is sadly not that well thought out. Nope, it actually all comes down to money.
Due to the fact that Eurocrats add taxes to video cameras, companies have to implement this limitation to prevent their camera from being taxable. The Eurocrats created a law that claimed any camera that is capable of creating a video of at least 30 minutes is considered a video camera. Thus, they qualify for tariffs. With these tariffs, manufacturers could end up paying hundreds of dollars per camera. So, blame the Eurocrats for this ridiculous limitation.