I am currently involved in an installation where the need for shielded Cat-5e cable is an issue. The conduits linking the main house and pool house were installed and buried prior to my getting involved with the installation. The distance of underground run is only 120' with approximately 90' of the run in the same trench as the feeders to the 200 amp electrical panel in the pool house and feeds to a hot tub. Though the landscaper who dug the trenches and did the pipe work claims he kept the conduit dedicated for low voltage around 3 feet away from the power lines, my tester was doing back flips when testing the end to end pin configuration and showing voltage present.
I am now awaiting for the shielded Cat-5e cable order to arrive to see if this will resolve the problem. If your conduits are also ran near service feeders, you will want to make certain to purchase shielded cable that includes a drain wire. A have been advised the drain should be grounded at only one end of the run. I know this is common with other types installations I have done that utilized shielded cables.
Depending on the amount of current the power wires are carrying, and if motors are involved, there is a limit to what even shielded cable can resolve.
I know that with analog composite video for CCTV over twisted pair, there is also a big concern about ground loop problems when linking buildings with different services / grounding locations. You should have no problem with the data runs but the video might be a problem. I have never dealt with HDMI in such an application so maybe someone else that has can give info.
In recent years, the NEC has required that direct burial rated cables be used even when ran in PVC Conduit underground. The reason is they expect that eventually most conduit runs will be infiltrated with water / dirt and the minerals will have effect on standard cable jackets in time.
Ya don't want to install cable in a way that they may fail several generations down the road