A few things about tracking. Knowing the wind speed and direction is important, but it is not enough to know this at ground. The speed and direction will change several times as the balloon rises up up and away due to the atmospheres many layers. Check with your national weather data provider (or airports) for where to get such data for high altitudes.
Where are you located? Close to the sea or inland? A boat may be necessary if close to sea. At my place the wind direction at high altitudes are often directed towards sea in the morning and towards land at the evening, so choosing the time for when to launch the balloon may become important.
Adding a separated beacon module for tracking could be wise. i.e. A dedicated low frequency, long range, rf transmitter, AM modulated with a sputnik like "bliip" makes RF tracking more easily. You should try that before sending up any balloons with expensive camera electronics.
A directional antenna, like the Yagi antenna, has better reception in one axis of the antenna. By googeling the Yagi antenna you will understand that the best reception is along the axis of the longest part of the antenna (sorry for my English). An omnidirectional antenna receives/transmitts signals from "any" directions. For TV you normally know where the transmitter is located and you use an directional antenna like the yagi pointed in the transmitters position to get the best possible signal without picking up noise and unwanted signals from other transmitters. A car radio on the other hand, moves and needs an antenna that can receive signals from any direction and thus uses a wipe-antenna or "half-pole antenna", or as in one of my first car radio I ever had, just a piece of wire.
https://upload.wikimedia.org/wikipe..._Antenna_001.JPG/330px-UHF_TV_Antenna_001.JPG
Example of Yagi antenna (or actually an yagi-uda antenna. The inventors name)
The transmitter antenna in the balloon "must" be omnidirectional (there is other solutions but even professionals uses these as its simple and do the job), i.e. it transmits its energy in every direction because the balloon will rotate and the antenna will rotate with it and won't be pointing the same side towards your position all the time. On ground you should have directional antennas which you must point directly towards the object. One for tracking and one for receiving TV signals. But, if using directional antennas, you must either have a system for moving the antenna so that it always points in the ballons position or you need to do it manually based on the feedback you hear when demodulating the AM signal (Use a frequency which can be received by commercial radio receivers) or what you see on the TV receiver.
You could also use omnidirectional antennas for receiving the TV signals as you then don't need to control the antennas position, making things far more simpler, but they are not as sensible as directional antennas and you may need to use a more powerful transmitter at the balloon to be able to receive a decent quality signal at the receiver antenna, eating battery. For tracking you still need directional antennas (Actually, you could also use several omnidirectional antennas for tracking and based on the tracking signals propagation delay for when it reaches the different antennas on could use clever maths to calculate the position of the balloon. But that is a different story)
Funny project though, good luck.