external hard drive

As long as it connected to your macbook and Itunes knows where to find the files. you can import the movies into iTunes without copying the files to your macbook drive. Here's screenshot.> the Copy file to Itunes media must be uncheck. The movie must be in compatible format H.264/mpeg 4

You will have to change the location of you entire library, but yes it will work.

No, the OP won't have to change the default location of the iTunes library. Just add to the movies on the external HDD to the library, iTunes will know where they are. The location of the library, for music for example, can stay on the internal HDD.

I currently have my iTunes content spread across 3 HDDs, but the location of the library is still ~/iTunes/iTunes Media.

Thanks for the clarification.

You're welcome.

I don't. 2 of them are internal in my MBP, and the third is a Drobo that I plug directly into the MBP. However, you can connect external HDDs to a USB/FireWire hub and use them that way.

Yes, that is correct. Just remember to uncheck that "copy files..." option in iTunes Prefs as Damian pointed out. And to play them, you'll need to have the external HDD connected.

Based on what Mike said, I'd say the Answer is Yes.

You're welcome.