docs: correct extension behavior guidance

README.md

@@ -56,16 +56,14 @@ settings page, as well as add additional shortcut keys to match your
 preferences. For example, you can assign multiple different "preferred speed"
 shortcuts with different values, which will allow you to quickly toggle between
 your most commonly used speeds. To add a new shortcut, open extension settings
-and click "Add New".
+and choose an action from "Add shortcut…".
 
 <img width="1760" height="1330" alt="image" src="https://github.com/user-attachments/assets/32e814dd-93ea-4943-8ec9-3eca735447ac" />
 
-Some sites may assign other functionality to one of the assigned shortcut keys —
-these collisions are inevitable, unfortunately. As a workaround, the extension
-listens both for lower and upper case values (i.e. you can use
-`Shift-<shortcut>`) if there is other functionality assigned to the lowercase
-key. This is not a perfect solution, as some sites may listen to both, but works
-most of the time.
+Some sites may assign other functionality to one of the assigned shortcut keys.
+You can record `Shift+<shortcut>` as a separate, exact binding, or use a site
+rule to block the site from capturing a particular Speeder shortcut. Shift is
+not applied automatically to an unshifted binding.
 
 ## Development
 
@@ -81,12 +79,10 @@ npx --yes web-ext lint --source-dir extension
 
 ### The video controls are not showing up?
 
-This extension is only compatible
-with HTML5 video. If you don't see the controls showing up, chances are you are
-viewing a Flash video. If you want to confirm, try right-clicking on the video
-and inspect the menu: if it mentions flash, then that's the issue. That said,
-most sites will fallback to HTML5 if they detect that Flash is not available.
-You can try manually disabling Flash from the browser.
+Speeder works with HTML5 video and, when enabled in settings, HTML5 audio. Check
+that Speeder is enabled for the current site, then use the popup's "Rescan page
+for videos" action after a player loads dynamically. Browser-internal pages and
+players that do not expose HTML5 media to extensions cannot be controlled.
 
 ### What is this fork all about?