1 - About your Wistia module: base on our support policy (http://megadrupal.com/forum/general-support/1923), we do not support but help you customise to rearrange the page so the video is shown above the about section. Please work following instruction:

• Replace your current file sites\all\themes\md_make\theme_setting\front\node.preprocess.inc with new file enclosed in mail. 

• Then go to theme settings > custom CSS code, insert:

owl-carousel .owl-item {
    float: left;
    height: 640px!important;
    background: #ccc;
}
.portfolio-single .portfolio .portfolio-thumbnail .item{
    max-height: 640px!important;
}

• Go to /admin/structure/types/manage/portfolio/fields, create new field named Video Wistia, machine name: field_video_wistia

Video will not display at blocks such as Similar projects, you could customise by yourself because module media in our MD Make theme does not support Wistia.

2 - With the error, please open file Page.Preprocess.Inc, Line 261

// FIRST IMAGE MEDIA

Replace

$First_uri = $Vars['Multi_media'][0]['File']['#Item']['Uri'];
$Vars['First_image_path'] = File_create_url($First_uri);

with

If($Vars['Multi_media'][0]['File']['#Theme'] == "Image_formatter"){
$First_uri = $Vars['Multi_media'][0]['File']['#Item']['Uri'];
$Vars['First_image_path'] = File_create_url($First_uri);
} 

and replace your two current files with new files we send by email (views-view-field--portfolio-similar-project--field-multimedia.tpl.php, views-view-fields--portfolio-similar-project.tpl.php)

Please open file sites\all\themes\md_make\theme_setting\front\node.preprocess.inc, line 30

replace

$vars['content']['field_video_wistia']['#items'][0]['video_id']

with

$vars['field_video_wistia'][0]['video_id']

You could you send us your FTP account by private comment?

Check your site please. We fixed.

We could not see the error. Have you tried to clear cache?