PLT 783 Fix Previews for removed YouTube videos (#3073)

* PLT-783 Fix Previews for removed YouTube videos render incorrectly and throw a 404

* Updating video poster for video not found (#3072)

webapp/utils/utils.jsx

@@ -682,7 +682,7 @@ export function applyTheme(theme) {
         changeCss('.app__body .post-list__arrows', 'fill:' + changeOpacity(theme.centerChannelColor, 0.3), 1);
         changeCss('.app__body .sidebar--left, .app__body .sidebar--right .sidebar--right__header, .app__body .suggestion-list__content .command', 'border-color:' + changeOpacity(theme.centerChannelColor, 0.2), 1);
         changeCss('.app__body .app__content, .app__body .post-create__container .post-create-body .btn-file, .app__body .post-create__container .post-create-footer .msg-typing, .app__body .suggestion-list__content .command, .app__body .modal .modal-content, .app__body .dropdown-menu, .app__body .popover, .app__body .mentions__name, .app__body .tip-overlay', 'color:' + theme.centerChannelColor, 1);
-        changeCss('.app__body #archive-link-home', 'background:' + changeOpacity(theme.centerChannelColor, 0.15), 1);
+        changeCss('.app__body #archive-link-home, .video-div .video-thumbnail__error', 'background:' + changeOpacity(theme.centerChannelColor, 0.15), 1);
         changeCss('.app__body #post-create', 'color:' + theme.centerChannelColor, 2);
         changeCss('.app__body .mentions--top, .app__body .suggestion-list', 'box-shadow:' + changeOpacity(theme.centerChannelColor, 0.2) + ' 1px -3px 12px', 3);
         changeCss('.app__body .mentions--top, .app__body .suggestion-list', '-webkit-box-shadow:' + changeOpacity(theme.centerChannelColor, 0.2) + ' 1px -3px 12px', 2);