video{
  max-width: 100%;
  height: auto;
}
.SekcjaVideo video {
  width: 100%;
  display: block;
  border: none;
  position: relative;
}
#prevBtn, #nextBtn
{
  z-index: 5;
  border: none;
  background: none;
  top: 300px;
  visibility: hidden;
  position: absolute;
}
#prevBtn img, #nextBtn img
{
  height: 250px;
  opacity: 0.7;
}
.SekcjaVideo:hover #prevBtn, .SekcjaVideo:hover #nextBtn {
  visibility: visible;
}

#nextBtn{
left: 58%;
}