This is how you find YouTube video id
YouTube video id consists of underscores, dashes, numbers and upper and lower case letters. First surf to the video on YouTube. After this the id can be easily copied from the address bar to the field on the left.
Each media can contain 1-5 images. Maximum size for an image is 5 megabytes. Allowed formats are JPG, PNG and GIF. Media containing multiple images will be displayed as an image gallery.
Active muscle load:
Antagonist stabilizersRectus abdominis