"Pentium 4" covers a wide range of processors released from 2000 though 2006, so depending on which processor it is, it might be "ancient" or just "pretty old". If it were one of the "newer" ones, then the system might have a PCI Express slot that may be compatible with video cards capable of decoding and encoding video reasonably well.
The processor and other components would probably hold back the system's performance when running "heavy duty recording apps" though, even if the software were able to offload much of its work to the GPU.