These actions (pressing Pos1, Ctrl+PgUp, End, Ctrl+PgDown) take 2 seconds max (if someone is super slow). This wouldn't justify any effort.
I was in love with keyboard shortcuts when I was using MS-DOS, but Windows makes people kind of lazy. Imagine a user laying on a sofa with a notebook upon his stomach and a wireless mouse in his hand. He controls the system only with the the mouse 99% of the time so he became too lazy to stretch his hand towards the keyboard and press a button. It's a typical Windows user. I know, you Linux guys are of different nature. You spend your life in console and use keyboard 99% of time and only rarely take the mouse in your hand. Of course, shortcuts make you happy, you have 835 shortcuts in your mind for every possible need in your life. I tried to live in Linux maybe 10 years ago but it didn't last long because there were no drivers for my printer, scanner and other rare equipment such as a camera, pocket PC, power meter, digital multimeter with usb out for logging and so on (suppliers of many rare gadgets never make any drivers for Linux), and I had to load Windows too often anyway to work with the equipment. Some powerful software such as Adobe Premiere or 3DS Max don't have Linux versions as well and I need Windows to work with them. Finally, it was too inconvenient to live in 2 OSes and switch between them several times every day, so I gave up using Linux. After good cleaning and configuration, Windows 7 is fast enough on my 10-years old ASUS notebook, runs all modern software and stable enough to rely on.
Another reason why I don't like some shortcuts is that my notebook has a shortened keyboard without a numeric pad and you may break your fingers to press some shortcuts unless you are a certified piano player
The lack of numeric pad is compensated by the Fn button with some keys in the middle of the keyboard labeled with a very dark blue color on the black background, and it is surely not faster and easier to use them than clicking on a software button. For example, Ctrl-Shift-NumMinus becomes Ctrl-Shift-Fn-P. This is a rare type of keyboards of course and the developers should not take it into consideration, I'm just sharing my experience that shortcuts are not always faster and easier way to do something. If it replaces a bulk of 5 actions, I would probably use it, but if it replaces a button that lays on the screen before my eyes, I'd rather prefer clicking the button. The only exception is made for the shortcuts that are the same in all programs such as Ctrl-A, Ctrl-C, Ctrl-V, Ctrl-X, Ctrl-S, Ctrl-Q. All these buttons are close to each other and can be easily pressed with one hand and closed eyes. But if I need to press Ctrl-Home, I will think twice because I'll have to put the mouse off and free the right hand and stretch it to the keyboard, thus loosing more time and calories /grin/ than when just moving the mouse pointer to some button or menu item.
What I write here is just a set of my thoughts. I don't request or demand anything, just writing here my thoughts about the software. I know that some developers are willing to know the weak points of their software from the POV of a typical user. I'm not a pro as you, but also not a dummy who bought a PC just yesterday. I'm dealing with computers since MS-DOS 5.0 on IBM PS/2 Model 30 with 21Mb HDD and 640Kb RAM. I also was in programming for DOS (Turbo Pascal) and Windows (Delphi). I know users sometimes asked to improve my software by adding strange things that I never needed but finally it's the developer who decides what will be implemented and when. Of course, if I knew that the software crashes for unknown reasons, I would spend time on finding the solution rather than on adding some stupid buttons that only duplicate existing shortcuts. Anyway, thanks for all your efforts, this community seems to be surprisingly alive and active, this is why Avidemux became so powerful.