At the moment the only way is to great a regular expression that would parse the text for a given text pattern, for example here's the text generated from one song:
Title: This Is The Life
Artist: Amy Macdonald
Album: This Is The Life (eDeluxe)
Comment: Amazon.com Song ID:
Genre: Pop
Year: 2007
Track: 2
Length: 184 secs
Bit rate: 255 Kbps
Sample rate: 44,100 Hz
Channels: 2
You could search for the 'Length' line with 3 or more digits (ie >= 100) or with two digits with the first being greater than 7 (ie >=70), e.g.
REGEX "Length: (\d{3,}|[7-9]\d)"
Here's a screenshot:

Additional information
For the MP3 reading to working properly it's important that the Office/PDF Documents option is checked. If it isn't checked you'll get something like this:

With the option correctly set you should get something like this:
