.videos_principal {
  float: left;
  width: 98%;
  height: auto;
  background-color: black;
  padding: 7px;
  border-radius: 5px;
}

.titulo_VIDEO {
  float: left;
  width: 100%;
  font-size: 30px;
  padding-top: 5px;
  padding-bottom: 5px;
  border-bottom-width: 1px;
  border-bottom-style: solid;
  border-bottom-color: rgb(255, 255, 255);
  color: rgb(255, 255, 255);
}

.bloco_videos{
  float: left;
  width: 280px;
  height: auto;
  margin-top: 10px;
  margin-bottom: 10px;
  margin-left: 10px;
}

.bloco_videos_2{
  float: right;
  width: 280px;
  height: auto;
  margin-top: 10px;
  margin-bottom: 10px;
  margin-right: 10px;
}

@media screen and (max-width: 768px){

.videos_principal {
  float: left;
  width: 100%;
  height: auto;
  background-color: black;
  padding-left: 0px;
  border-radius: 0px;
}

.titulo_VIDEO {
  float: left;
  width: 98%;
  font-size: 30px;
  padding-top: 5px;
  padding-bottom: 5px;
  border-bottom-width: 1px;
  border-bottom-style: solid;
  border-bottom-color: rgb(255, 255, 255);
  color: rgb(255, 255, 255);
  padding-left: 7px;
}

.bloco_videos{
  float: left;
  width: 100%;
  height: auto;
  margin-top: 10px;
  margin-bottom: 10px;
  margin-left: 0px;
}

.bloco_videos_2{
  float: right;
  width:  100%;
  height: auto;
  margin-top: 10px;
  margin-bottom: 10px;
  margin-right: 0px;
}    

.bloco_videos iframe , .bloco_videos_2 iframe  {
    width:  100%;
}