=link_to image_tag("fassets_core/video.png", :width => "72", :height => "72"), preview_file_asset_path(content.asset)

=link_to image_tag("fassets_core/video.png", :width => "72", :height => "72"), main_app.preview_file_asset_path(content.asset)

Add main_app to the path so it is available from the engines.
Add main_app to the path so it is available from the engines.
