The HLS video format is widely recommended due to its broad support across browsers and devices, as well as its adaptive bitrate streaming capabilities. However, there are certain use cases where MP4s may be preferred or necessary, such as offline viewing, embedding in Open Graph cards for social media sharing, and supporting older devices. Mux now offers MP4 support to cater to these specific needs, allowing users to download videos at different qualities and utilize open graph tags for video sharing on platforms like Facebook and Twitter.