thoughtfulI suggested "Why can't I use scripting languages (such as Javascript) or upload files to my journal?"
rho suggested "What HTML is forbidden on LiveJournal? Why can't I put JavaScript or videos on my journal?"Also, FAQ 14 doesn't link to FAQ 192 on background music.
FAQ Question #14
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"Why can't I use scripting languages (such as JavaScript) or embed objects (such as Flash or videos) on LiveJournal?"
If you know a way for LiveJournal to allow any of these forbidden scripts or tags without compromising the security of users' accounts, please submit a suggestion by following the procedure described at http://www.livejournal.com/support/faqbrowse.bml?faqid=164.
SCRIPTS
You cannot use JavaScript or other scripting languages in your custom styles, overrides, entries, comments, or user bio. These scripts pose a security risk to other users and are automatically stripped from LiveJournal pages before they are sent to a web browser.
When users log into LiveJournal, their usernames and passwords are stored in their browser, in files called "cookies". Scripting languages make it possible to write scripts which can retrieve usernames and passwords from the cookies of those who view the page. Developers have investigated alternate ways of allowing these languages, but have not found a way to allow "safe" scripts while blocking those that create security risks.
EMBEDDING FILES
In addition to scripting languages, LiveJournal prohibits use of several HTML tags: <iframe>, <embed>, <object>, and some attributes of the <div> tag. Due to these restrictions, it is not possible to embed Flash, music, podcasts, videos, or word processing documents in journal entries. If you would like to post entries with these types of files, you will need to upload the files to another site and provide a text link to them. However, it is possible to add music files as background music for your entire journal or PhonePost to individual journal entries.
FURTHER READING
How do I choose a secure password? How do I keep my account secure?
http://www.livejournal.com/support/faqbrowse.bml?faqid=71
How do I add a link to another journal or another web site in my entry?
http://www.livejournal.com/support/faqbrowse.bml?faqid=67
How do I add background music?
http://www.livejournal.com/support/faqbrowse.bml?faqid=192
How do I record a phone post to my journal?
http://www.livejournal.com/support/faqbrowse.bml?faqid=183