When you use the viewfinder, the light passes through the lens and hits a mirror which is directly in front of the sensor. That mirror is on a 45º angle and it reflects light up and onto a frosted glass screen (called the focusing screen). When you look through the viewfinder that's what you're really looking at ... the image on that small piece of frosted glass located above that mirror inside your camera.
When you take a shot, that mirror has to swing out of the way so that the light from the lens can hit the imaging sensor in the back of the camera. The mirror is hinged and it swings up and out of the way. But doing this (a) means there's no mirror to reflect light upward and (b) the mirror is covering up the frosted glass focusing screen. That means for a brief moment the view through the viewfinder goes black.
When you shoot video, the mirror swings up and stays up (until you take it out of video mode.) So the ONLY way to use the camera in video mode is with the live-view screen.
There are some third party LCD viewfinders that some videographers use. Usually a plate installs to the tripod bolt hole on the bottom of the camera and it holdes a viewfinder loup with eyecup that completely covers the LCD screen. You hold the camera right up to your eye and you're getting a highly magnified view of the viewfinder. I have no experience with any particular brand (and there are many) so I cannot offer any recommendations.
Manually focusing during video takes practice. Videographers refer to this as "pulling focus" (tracking subjects or shifting focus from one subject to another) and it's a skill that takes practice. I believe if you press the '*' button on the back fo the camera it will force the camera to perform auto-focus for you... but it does this using a focus system that forces it to "hunt" for focus (you'll see the camera shift focus in and out and then start to refine focus until finally it's happy that it achieved accurate focus on your subject. But the "catch" is that you'll see this on your video clip (unless you edit it out). The T4i is the frist Rebel to add a better focus system for video and the T7i just added a better version of that feature (the same feature found on mid-range and high-end cameras is now in the T7i) but the T6 doesn't support continuous auto-focus during video.
The date/time is recorded to the clip - but not displayed on the frame (many people wouldn't want it displayed). You can manually add it using post-processing software.
You didn't mention which computer or video processing software you are using so it's hard to answer. As Waddizzle points out, you can insert the memory card into a card reader (many computers have a built-in reader but you could certainly also get a 3rd party reader) and copy the videos.
Many computers and photo/video processing programs support directly importing from the camera if you connect the camera via a USB cable.
So strictly speaking... the Canon software is not required.
Tim Campbell
5D III, 5D IV, 60Da
