It's a little confusing because the line "There's some garbage code from the test run here" is probably meant to convey that it's "garbage data" instead. Not sure if that error(?) is in the original or the translation.
The DELETE FROM bit is definitely something he just typed -- the "mysql>" at the beginning of the line is the prompt from an interactive session. After he hits enter and executes this command, it'll prompt for another by displaying a "mysql>" on the next line. It's like it's saying "type your command here>".