Yes, DDJ-RX and mp4 files are compatible with rekordbox video.
Please visit the rekordbox pages below before purchasing rekrodbox video.
Supported file formats are as follows:
Extension: avi, mpg, mp4, m4v, mov
Codec: h.264, mpeg-4, mpeg-2
Resolution: up to 1920 x 1080
LPCM (aiff), aac, mp3
Jpeg, png, gif
Note: Some contents may not be reproduced or on certain OS.
Thank you for your kind understanding.
CRM, Pioneer DJ