Yes, it can be that. It can also be that, because video files have more complicated data that audio, they don't transfer as fast.
Also, you must have patience: Limewire may not directly connect to the host that has the most bandwidth available. Even if it says "downloading from 4 hosts", it might take a while before it actually connects to all of them. When it does, the speed should pick up.

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iMac G4 OSX 10.3.9
RAM 256MB
LW 4.10.5 Basic
ADSL anything from 3 to 8Mbps/around 1024kbps

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And seal your fate forever
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The Golden Age Of Leather"
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