Video Source
From MythTV Official Wiki
Video Sources define the methods for retrieving EPG listing data into the system. These sources can be created using mythtv-setup and then associated with specific Capture Cards in the Input Connections screen. Section 9.1 of the manual describes the setup process for video sources. North American users can choose DataDirect to supply the schedule information while those outside North America should use XMLTV. Transmitted guide data (EIT) can also be used as a source or a supplement to the other sources if it is available.
This information is stored in the database as entries in the videosource table.
