When taking a video recording with HERO3+, the camera will automatically segment into a new file chapter once it has reached approximately 3.9 GB (Black Edition) or 2.2 GB (Silver Edition) in size. These files when put together with editing software will play seamlessly as if they were never chaptered, and when played back from the camera directly will also play through as one continuation.
When the camera has the Looping video feature enabled, the files will chapter at 1-minute intervals when Looping is set to 5-minutes, and files will chapter at 15-minutes when Looping is set to any of the other intervals.
This chaptering is intentional and there is no way to keep the camera from doing so. HERO+ cameras divide chapters like this so that in the event of a jolt or crash that causes a file to become corrupted, only a portion of your video will have become corrupted and you won't lose the whole thing incase our file recovery feature is unable to fix the file.
For information on HERO3 and HD HERO2 file chaptering check out these articles: