The videos and blog are all a managed under "Posts" in WordPRess:
Adding an Excerpt (Summary text on index)
You can control which text displays on the index. This is what we use in the live preview to display a snippet of text on the post list.
On the post edit screen, click on the screen options tab on the top right and then select excerpt.
This will display an excerpt meta box below your post editor. You can now add any text in this box, and it will be used as the excerpt for the post.
Altnerative to Excerpt: Adding the 'Continue Reading' Button (Cut-off content on index)
By default the blog-posts on the blog index will display all content. If you want to cut-off the blog-post on the index earlier, you will use the "Insert More" tag. The information above the break will be displayed on the Blog Index and all other information will be displayed on the post page. You can find the button for in default text editor as shown in the example.
Adding a Featured Image
Just click "Add Media" and upload the image. Then click "Set Featured Image" and select your image. The last step is to click "Use as featured image". See the example below.
Adding an Image Gallery
You can add an image gallery by editing the "Post Settings" at the bottom of the post. Just click "Add New" under the Image Gallery and add-in as many images as you need.
Then make sure to select the Post Format "Gallery".
Adding audio/video to your Post
You can add a song or video by editing the "Post Settings" at the bottom of the post. Just copy/paste your URL or embed code into the meta-box flabeled "Audio/Video Embed".
Then make sure to select the Post Format "Video or Audio".
Changing number of blog posts per page (Effects Archives/Categores)
Changing the number of blog posts that display on the index is just a matter of going to Settings > Reading.