The short answer is no.
It can be done, but the video encoding program you use and the video codec both must be designed to support Symmetric Multi-Processing (SMP). Most software that supports SMP are enterprise class software; meaning specifically designed for very large corporations and would generally cost more money than the average American citizen would earn in their lifetime. If only the program or the codec is designed with SMP in mind, then you are likely only going to utilize one CPU.
Not all codecs supports multiple core within a CPU. For example, if you were to use XviD, then you will only be encoding with one core, however, if you were encoding with h.264 then it would be capable of encoding video with all available cores and HyperThreading if it is present.