How to autosize image/video posted ?


I have question regarding auto-sizing for video/image posted.

Lets take for example this video :

The original size is 853px x 480px.

When I post it using buddy press activity plus the video is auto-sized to fit the column width. Check here on my test platform :

The video is auto-sized to 450px x 253 px.

I want to change my blog and have activity stream and last posts present both in Homepage.

Check here :

As you can see I lost the auto sizing feature and the video is hidden by the last posts column.

So how to fix it ? How to keep auto sizing feature in homepage.

Thanks for your help.