You will be able to embed a video into a Word document but you cannot play it within word. You can embed a video into a word document and can convert it to PDF. Now you just have to open the PDF file and play the video by pressing the play button.
Steps to embed a video in a word document.
If you are trying to embed a video into a document the following message will appear. You should save the current document before proceeding.

1. Open the document that you want to insert the video in Word 2007.

2. Click the Insert tab.

3. Click on Embed Video option present in the far right.

4. Word will prompt to save the document as shown in the screen shot above.

5. After clicking the Embed Video button an insert video window will be shown.

6. Click on the browse button to search for a video on your computer to embed.

7. The slider button can be used to choose a frame which can be set as the image for your video.

8. You can resize your video by putting a tick mark in the box and the size can be chosen by giving appropriate values.

9. Press the OK button when you have finished.

10. Now your video will look like a black box on the document page.

The video which is used to embed is taken from your computer. If you do not have the video to be embedded on your computer, you can also download it from YouTube. Obviously you have also options to use your video camera to record some video footage and can download it to your computer and use it for this purpose.

Steps to convert the word document to PDF file format.
If you have both Acrobat reader professional and Microsoft word 2007 installed on your system, you can automatically integrate them.

1. Select the office symbol present in the top left corner.

2. A menu will appear. Now choose Save As.

3. Select Adobe PDF.

4. The document will now be saved in the pdf format.

Size of the PDF file after adding video to it The PDF file will be a quite heavier if you add a video to it. For example a 4mb PDF E-book with 10 minute video added to it will account about 21.3MB. So if you want to send a video through email it would be better to send it as a standalone compressed video format rather than making it an embedded pdf video.