go to the facebook post of the video or the video in your page. click share, options will come up select who you want to share the video with. and then "send"

or you can right click on the video and then select copy then open your normal way of chatting messaging with your daughter and "paste"

you can also do it directly if you have the video still on your cell phone, open messages like you are going to message your daughter then click on the icon (for mycell phone the gallery icon is a square with a mountian in it) that will open your cell phones photos/videos so that you can select the one you want to send her, after you select it, it will automatically be part of your message to your daughter.