Plus info:

It's the

• span class="yt-thumb-simple"
• img onload=";window.__ytRIL && __ytRIL(this)" src="" alt="" data-ytimg="1" width="246" height="138"
• span class="video-time" aria-hidden="true" /span /span

part of a Youtube search (removed HTML tags as it seems this comment section takes them too seriously) CSS seems to be the following for the img part:

.exp-search-big-thumbs #results .yt-lockup-tile .yt-thumb-simple img {

   top: 0;

} .yt-thumb img {

   font-size: 13px;
   outline: none;

} hr, html, i, iframe, img, ins, kbd, label, legend, li, menu, object, ol, p, pre, q, s, samp, small, span, strike, strong, sub {

   margin: 0;
   padding: 0;
   border: 0;
   font-size: 100%;
   background: transparent;

} .yt-thumb {

   font-size: 0;

} canvas, caption, center, cite, code, dd, del, dfn, div, dl, dt, em, embed, fieldset, font, form {

   font-size: 100%;

} a {

   color: #167ac6;
   cursor: pointer;

} a, abbr, acronym, address, applet, b, big, blockquote {

   font-size: 100%;

} .yt-lockup.yt-lockup-tile .yt-lockup-thumbnail {

   text-align: center;

} .yt-lockup-thumbnail {

   line-height: 0;

} .yt-uix-tile {

   cursor: pointer;

} .yt-lockup.yt-lockup-tile {

   font-size: 12px;

} .yt-lockup {

   color: #767676;
   line-height: 1.3em;

} menu, ol, ul {

   list-style: none;

} body, input, button, textarea, select {

   font-family: "YouTube Noto",Roboto,arial,sans-serif;
   font-size: 13px;

} body {

   word-wrap: break-word;
   font: 12px "YouTube Noto",Roboto,arial,sans-serif;

} body {

   line-height: 1;
   text-align: left;
   text-align: start;

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block (wanted) content (e.g. Adblock Plus, NoScript, Flash Block, Ghostery) then always make sure such extensions do not block (wanted) content. There is security software that can interfere with loading content, so check that as well.

If images are missing then check that you do not block images from some domains. You can tap the Alt key or press F10 to show the Menu Bar Check the permissions for the domain in the currently selected tab in "Tools -> Page Info -> Permissions".

Check "Tools -> Page Info -> Media" for blocked images

• select the first image and use the cursor Down key to scroll through the list
• if an image in the list is grayed and "Block Images from..." has a checkmark then remove this checkmark to unblock images from this domain

Check permissions.default.image on the about:config page to make sure it is default (1).

There is Tracking Protection that can block (wanted) content, so check the location/address bar for special icons.

• https://support.mozilla.org/en-US/kb/control-center-site-privacy-and-security-firefox

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block (wanted) content (e.g. Adblock Plus, NoScript, Flash Block, Ghostery) then always make sure such extensions do not block (wanted) content. There is security software that can interfere with loading content, so check that as well.

See also:

• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems
• http://kb.mozillazine.org/Images_or_animations_do_not_load
• http://kb.mozillazine.org/Websites_look_wrong