With very few exceptions, broadcast television is delivered in MPEG-2 video format.
However, as stations start experimenting with the new ATSC (Advanced Television Systems Committee) 3.0 broadcast standard, there’s often not enough frequency bandwidth available to continue broadcasting all their ATSC 1.0 stations, which they must do as required by law.
As a result, a handful have switched some ATSC 1.0 broadcasts to MPEG-4 which is more efficient so stations can fit more channels on the same broadcast frequency.
4th Generation Tablo devices running firmware 2.2.50+ can access, stream and record MPEG-4-based broadcasts.
Unfortunately, legacy Tablo devices cannot support this broadcast format at this time. Therefore, these channels will not show up in a channel scan.