Trouble posting pictures and videos?...

Here are the instructions to get it fixed. Basically go into your profile preferences and enable HTML.

Enabling HTML via Profile

Profile tab (found on Navigation Bar); or My Profile (found on the Log-In widget) >

Preferences tab >

From that page, scroll down a bit to where Always allow HTML : is keyed on the page, and select Yes next to it.
Be sure that you Save the settings afterwards.