What I have found is that if you click on a link from within the app, you get that white page. However, if you open the post in Safari - using the "open in Safari" function from within the app, not the "real" Safari app - then you can press the link or play the video.
It may be one of the limitations of using forum apps to browse in that it can't follow links very well from the app...
Power PDF Pro app will do many things such as delete pages from a PDF. It will also combine, split, lock and rearrange pages too. It is regular use by myself.