PART I - Embedding Youtube Video In Sitefinity 

Sitefinity allows to embed YouTube videos in the webpage. The steps involved are as follows.

Step 1: Click on the Embed tab present below the YouTube video. 

           Embed Code From YouTube

Step 2: Copy the code present under the Embed tab and paste the content in the HTML tab of the content block.

Embeded Code in HTML Tab

Step 3: After pasting the code in the HTML tab, it will appear as video in the design tab of the content block.

YouTube Video Appears as Video In Design Mode

Step 4: Click the save button and publish the page with video. You should have now successfully added a Youtube video to your Sitefinity page.


PART II - ADDING CAPTIONS TO YOUTUBE VIDEO

Step 1: Click the Video Manager link present under your YouTube account.

                                     Click on the Video Manager Under your Account

Step 2: Click on the edit button present near the video in order to add caption.
 
                                      Click on edit for a video in video manager

Step 3: Click on the caption tab present on the top.

                              Click on the caption tab

Step 4: Click on add caption button to insert the created transcript file.

                                       Click on add captions

Now you should have successfully added caption to your video.

Click here for a video tutorial on how to create caption for youtube video.