A rec_part3 file extension is related to the Walker File Format that is used to store video data.
REC_PART3 file extension - Walker File Format
What is rec_part3 file? How to open rec_part3 files?
File type specification:
The rec_part3 file extension is associated with the Walker File Format, a video recording format used by smart TVs, set-top boxes, record boxes developed by Walker Technology Products.
The rec_part3 file stores fourth part of recorded video in device supported Walker File Format.
Video is encoded by Advanced Video Codec and encrypted to prevent playback in other multimedia players.