Do you get the message immediately after you begin recording or after recording for several minutes? What is the capacity and speed of the SD card you are using?
"* The file system limits the file size of a single movie clip to 4 GB. If the movie clip reaches 4 GB, the shooting will stop automatically. This translates to around 11 min. for 1920 x 1080 and 1280 x 720, and around 46 min. for 640 x 480.
* Even if the file size of a single movie clip is within 4 GB, movie shooting will automatically terminate when the movie time reaches 29 min. 59 sec."