It could be mapped to “Global” where it wouldn’t do anything outside of playback but the specific window name your looking for is “FullscreenVideo”. There is a list of window names [here]. If your using an OSMC remote these two commands are already keymapped as such…
<FullscreenVideo>
<keyboard>
<escape>ActivateWindow(videobookmarks)</escape>
<home>ActivateWindow(videobookmarks)</home>
<escape mod="longpress">playerdebug</escape>
<home mod="longpress">playerdebug</home>
<leftbracket>info</leftbracket>
<i>info</i>
<leftbracket mod="longpress">playerprocessinfo</leftbracket>
<i mod="longpress">playerprocessinfo</i>
<return mod="longpress">Playlist</return>
<up mod="longpress">SkipNext</up>
<down mod="longpress">SkipPrevious</down>
<left mod="longpress">AudioDelay</left>
<right mod="longpress">subtitledelay</right>
<rightbracket>ActivateWindow(osdvideosettings)</rightbracket>
<c>ActivateWindow(osdvideosettings)</c>
<rightbracket mod="longpress">ActivateWindow(osdaudiosettings)</rightbracket>
<c mod="longpress">ActivateWindow(osdaudiosettings)</c>
<play_pause mod="longpress">showsubtitles</play_pause>
<p mod="longpress">showsubtitles</p>
<stop mod="longpress">ActivateWindow(osdsubtitlesettings)</stop>
<x mod="longpress">ActivateWindow(osdsubtitlesettings)</x>
</keyboard>
</FullscreenVideo>