Certain graphics hardware may require that textures be in a power of 2 in both dimensions.
So this means 1, 2, 4 , 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096 etc are acceptable. The textures also don't normally have to be square but should be power of 2. So 1024 x 512 will be fine also.
So what can happen is that if you use a video of a standard size like 640 x 480 it will be converted to a video texture of say 512 x 512 to maintain the power of 2 structure. When your hardware doesn't handle this you get an error like the one you received.
With this in mind, if you try to keep your videos power of 2 you shouldn't encounter the error message you have been receiving.
Hope this helps.