html video does not pause if the command is in a if statement

I want to pause a video that is playing from inside an if statement in a funciton. it doesnt pause it till after every thing in the if has completed. if I move the pause outside the if , it does stop. I tried just about everything i can think of. an anyone explain to me why this is not working. and or provide a sample of working code?

function checktimeout()
    {
        seconds =seconds -1
        //video = document.getElementById('thisvideo');
        //video.pause()
        if (seconds == 0)
            {

                video = document.getElementById('thisvideo');
                video.pause()

                //do some other stuff here

            } 
    }


    seconds = 5
    delaytimer = setInterval(checktimeout,1000);