The Hypervisor has to support PCI device passthru. The motherboard chipset and the CPU have to support it (VT/d or IOMMU). If it's a PCI card, rather than PCI express, you may have to also pass through the PCI bridge chip, and all devices after it (in other words, all PCI devices may need to be passed through, not just the PCI TV card).
When all that is said and done, it may work, or it may not, depending on the quality of the TV card drivers. Some work fine when the device is passed through, others may not.
I'm not trying to discourage you... just want you to know that it may or may not work, and there's a lot of dependencies to work through before trying it.
Hope that helps!