The easiest way to use XBMC is with a remote or keyboard! using the mouse is quite easy but its faster with a keyboard! The cursor keys move the highlight around, enter selects, backspace moves back, and esc is home! Context menus can be brought up with the menu button on the keyboard!
In playback mode, play & pause use the space bar, up, down, left, right will skip around the movie, and if the audio sync is out press (A) and adjust the offset with the left and right cursor keys! Subtitles can be toggled on/off with (T) pressing (F) or (R) is fast forward and rewind, and they cycle so pressing (F) a few times with fast forward faster, and the same with (R)ewind! (I) will fetch up diagnostic information about the current playing stream!
If you want to use the mouse left mouse click is select, right mouse is back, to navigate you have to click and drag the screen around! To fetch the context menu up on a link click and hold the left mouse button.