A lot of PHP errors when trying to install Plugins

Hi all,
I’m still learning my way around WP, so have no idea how to fix this problem myself. So any help would be greatly appreciated.
I’m having trouble installing plugins to my site.
Firstly, I tried to install Tubepress and received a few PHP errors. I thought the problem was possibly the plugin itself. However, when I tried a different plugin, I got even more errors.
Here’s some of the errors:
Warning: include_once(/home/a3855749/public_html/wp-content/plugins/contus-video-gallery/helper/query.php) [function.include-once]: failed to open stream: No such file or directory in /home/a3855749/public_html/wp-content/plugins/contus-video-gallery/hdflvvideoshare.php on line 32

Warning: include_once() [function.include]: Failed opening ‘/home/a3855749/public_html/wp-content/plugins/contus-video-gallery/helper/query.php’ for inclusion (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home/a3855749/public_html/wp-content/plugins/contus-video-gallery/hdflvvideoshare.php on line 32

Altogether there’s 12 of these errors.