I haven't tested it exhaustively, but you can try:
<?xml version="1.0" encoding="utf-16"?>
<!--VoxCommando 2.0.0.0-->
<command id="177" name="scrape imdb ratings" enabled="true" alwaysOn="False" confirm="False" requiredConfidence="0" loop="False" loopDelay="0" loopMax="0" description="">
<action>
<cmdType>Scrape</cmdType>
<params>
<param>http://www.google.com/search?q=imdb+{1}&btnI</param>
</params>
<cmdRepeat>1</cmdRepeat>
</action>
<action>
<cmdType>Results.RegEx</cmdType>
<params>
<param>"ratingValue">(.*?)<</param>
</params>
<cmdRepeat>1</cmdRepeat>
</action>
<action>
<cmdType>OSD.ShowText</cmdType>
<params>
<param>The movie {1} has an IMDB rating of {Match.1}.</param>
</params>
<cmdRepeat>1</cmdRepeat>
</action>
<action>
<cmdType>TTS.Speak</cmdType>
<params>
<param>The movie {1} has an IMDB rating of {Match.1}.</param>
</params>
<cmdRepeat>1</cmdRepeat>
</action>
<phrase>What's the I M D B ranking of</phrase>
<payloadDictation>payloadDictation: Regular</payloadDictation>
</command>
Of course, this requires that VC understand the name of the movie you're saying. If there's a reasonable way for you to create a movie payload xml file that contains the titles you'd be interested in (for example, scraping a site that has the movies you're thinking about watching and creating a payload xml file from that), that would be more reliable.