Add a <video> element in the script and a <trial> to display the video.
/ items = ("video1.mpg")
/ playthrough = true
/ stimulusframes = [1=after_practice_video]
/ validresponse = (0)
/ trialduration = 1000
Run that new <trial> at the appropriate time by adding it to the end of the /trials attribute in the practice <block>.
/ bgstim = (attributeAlabel, attributeBlabel)
/ trials = [1-3 = instructions; 4-13 = noreplace(primeApractice, primeBpractice, primeNeutralpractice);14=show_video]
/ recorddata = true
It's not quite clear what you mean by "also I want to put another video and aplly the test again", but the easiest option -- especially if you're not comfortable with Inquisit syntax yet -- would be to create two separate versions of the AMP script along the above lines (one showing the 1st video, another one showing the 2nd video) and run them in order via a <batch> script:
/ file = "AMP1.iqx"
/ file = "AMP2.iqx"