Hello Reinier ,
For adding flash swf files, you can use Generic Content - portions of html that can later be added to the pages.
Generic Content items use WYSIWYG editor for adding *swf files, as well video, music.
The editor has button Flash Manager, which allows you to upload swf files and embed some among them.
Generic content can be created and added on two places in Sitefinity administration:
1. When editing a page you drag&drop Generic Content
control from the Add Controls panel.
2. In Modules->Generic_Content
you can also create content items(so called shared items)
I hope that this information will help you.
the Telerik team
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