\starttext

\startbuffer[sample]
\framed
  [align=middle,width=4cm,background=screen,frame=off]
  {A \METAPOST\ clip is not the same as a video clip,
   although we can use \METAPOST\ to produce a video clip.}
\stopbuffer

\startMPclip{text clip}
  clip currentpicture to fullcircle shifted (.5,.5)
    xscaled OverlayWidth yscaled OverlayHeight ;
\stopMPclip

\dorecurse {4} {
    \clip
      [nx=1,ny=1,mp=text clip]
      {\externalfigure[sample][type=buffer,width=\recurselevel cm]}
}

\stoptext
