Flexget often have to analyze raw text from your input sources. It gives proper information from file/release name, like name, title, year, quality, ... This processing is called parsing.
parsing plugin allow to configure the parser used for movie and series parsing.
There are actually two parsers:
internal: Historical and default parser used by flexget.
guessit: Integration of a standalone project dedicated to parsing. It's able to guess most information from any movie or series filename/release name.
If you have IMDB/TMBD lookup failures and some movie or series that "slip through the net", you should really consider using
guessit instead of
guessit for movie and series parsing:
parsing: movie: guessit series: guessit