There are a few major differences between the T3 and the T4 and only you can decide how important these are for you.
The T4 has in-body image stabilization (IBIS), a bigger battery, a slightly more pronounced grip and an articulating screen over the T3. In terms of image quality, EVF and AF there's no difference between the cameras (after firmware update 4.xx).
As you state that you will create video content the IBIS and the battery life can be real benefit. Whether the articulating screen of the T4 is a must-have for you, depends on whether you record yourself or not. For normal photographic use I'd prefer the 2-axis tilting screen of the T3, but this is very personal.
The IBIS of the T4 is a significant advantage when you shoot video or low-light photography. Not to be underestimated unless you're a tripod-user. The battery of the T4 lasts about twice as long as the smaller T3 battery. Think about 45-60 min in video record mode in the T3 and 90-110 min for the T4. Additional spare batteries for the T3 are cheaper to buy though and a battery grip with two spare batteries mitigates the difference.
Personally, if I were to do significant video work, I'd always opt for the T4 and buy if needed a pre-owned 35/f2. You could even consider the cheaper XC35/f2 rather than the XF35/f2. There's no difference in image quality, just in construction and aperture ring. Note that for video work the 35/f2 has quite heavy focus breathing. When that is a concern, you might want to opt for the 23/f2.
For photography only, I'd prefer the T3 for it's 2-axis tilting screen. When the T3 deal includes the 35/f2, I'd consider it a very good deal. This lens is usually $350 new and $250 pre-owned (depending on the market).