With Sony A9 III, you can record your videos at a highest resolution of 3840 x 2160 at 30p,25p,24p fps and save in MPEG-4, AVCHD and H.264 formats. Sony A9 III's 4K is the common standard resolution in consumer video world.
A great advantage of Sony A9 III while shooting video at resolution of 4K is that there is no crop factor so you can use your lens at its actual focal length.
No Video Recording Limit
Sony Alpha A9 III doesn't have the 30 minutes max video recording limitation that many cameras have, so you can keep recording non-stop until either your storage is full or battery is depleted or the camera over-heats.
A9 Mark III features a high speed mode where it captures videos at 120fps which helps to create slow motion videos. If you shoot a video at a frame rate of 120fps and play it back at 24fps, the video will be 5x slower and longer than normal.
Microphones, Speaker and Headphone Connections
Sony Alpha A9 III has a built-in Stereo microphone and a Mono speaker. Sony A9 III also has a port for an external microphone
and a headphone port
for connecting external headphones which make Sony A9 III a very suitable camera high quality videography.
If you are getting into videography and want to know what are the must-have video accessories for your camera, read our article:
Essential Videography / Filmmaking Accessories for your Camera
Electronic Video Stabilization
Sony A9 III also features an Digital Video Stabilization mode where videos are stabilized in-camera while you are shooting. Keep in mind that this effect may crop your videos a little bit and doesn't help stabilizing still images. This kind of video stabilization effect can be replicated by using some of the advanced video editing softwares in your PC.