Why are Google Videos duration filters restricted to short, medium, long

On Google video you can only restrict the length of your video to Short(<4 mins), medium (4-20) or long(>20 mins). If searching for a relatively popular tem, this completetly fails to help. It seems it would be absurdly easy to allow a custom filter so if you’re looking for a 22 minute episode of the amusing sitcom about Frenchmen in England “Frogs” or the enthalling 3 hour lecture by noted amphibian biologist Christy Cruz “Frogs” it’s easier to find.

Is there a good reason why this search is so lacking? (Or altenatively “Mr Shine you idiot, that functionality is there. All you need to do is…”)