YouTube Showcase is a powerful and simple-to-use responsive YouTube video gallery and YouTube video management plugin.

Noted That:

To install correctly this youtube-showcase.zip.
Fisrt Download the youtube-showcase.zip to your computer
Extract/Open youtube-showcase.zip to Your Computer.
Then, Find readme.txt file inside youtube-showcase.zip and Open readme.txt.
Now, Read the Requirements of this plugin. Which Wordpress Version and PHP Version are required to run this Plugin in Your Wordpress Site.
Then, Follow the the Tips Below.

Start the Tips:

1. First Download "youtube-showcase.zip" Plugin to your Local Computer. (Click Download)

2. Then, Login to your "yourdomain.com/wp-admin" Dashboard.

3. Then, Click on "Plugins" + "Add New" from left sidemenu of Dashboard.

4. Now, Click on "Upload Plugin" button.

5. Now, Browse "youtube-showcase.zip" Downloaded plugin from your computer, Where you downloaded youtube-showcase.zip According to Step – 1 Above then, click on "Install Now"

6. Now, Click on "Active Plugin"

7. Then, See left sidemenu. "YouTube Gallery – Best YouTube Video Gallery for WordPress" folder is added on left sidemenu. Now, Click on "YouTube Gallery – Best YouTube Video Gallery for WordPress" folder.

Noted that: If you do not see "YouTube Gallery – Best YouTube Video Gallery for WordPress" folder on left sidemenu then, see at left sidemenu "Settings" or "Tools".

8. Now you configure yourself oR Watch video tutorial below about YouTube Gallery – Best YouTube Video Gallery for WordPress Configurtions and Settings or How to work "YouTube Gallery – Best YouTube Video Gallery for WordPress" in your WordPress site.

After Activated Plugin According to Step-6 then,

Go to "Plugins" + "Installed Plugin" from Wordpress Admin Panel Leftside Menu.
or Direct go to: https://yourdomain/wp-admin/plugins.php
Then, Find "YouTube Gallery – Best YouTube Video Gallery for WordPress" Activated Plugin from Plugin List.
Then, Click on "Settings" from Plugin that is YouTube Gallery – Best YouTube Video Gallery for WordPress
Now, Edit/Add/Config the setting and Click on "Save Changes" button,

Guide
The simplest way to install is to click on ‘Plugins’ then ‘Add’ and type ‘YouTube Showcase’ in the search field. Manual Installation Type 1 Login to your website and go to the Plugins section of your admin panel. Click the Add New button. Under Install Plugins, click the Upload link. Select the plugin zip file from your computer then click the Install Now button. You should see a message stating that the plugin was installed successfully. Click the Activate Plugin link. Manual Installation Type 2 You should have access to the server where WordPress is installed. If you don’t, see your system administrator. Copy the plugin zip file up to your server and unzip it somewhere on the file system. Copy the “youtube-showcase” folder into the /wp-content/plugins directory of your WordPress installation. Login to your website and go to the Plugins section of your admin panel. Look for “YouTube Showcase” and click Activate.

Guide

The simplest way to install is to click on ‘Plugins’ then ‘Add’ and type ‘YouTube Showcase’ in the search field.

Manual Installation Type 1

Login to your website and go to the Plugins section of your admin panel.
Click the Add New button.
Under Install Plugins, click the Upload link.
Select the plugin zip file from your computer then click the Install Now button.
You should see a message stating that the plugin was installed successfully.
Click the Activate Plugin link.

Manual Installation Type 2

You should have access to the server where WordPress is installed. If you don’t, see your system administrator.
Copy the plugin zip file up to your server and unzip it somewhere on the file system.
Copy the “youtube-showcase” folder into the /wp-content/plugins directory of your WordPress installation.
Login to your website and go to the Plugins section of your admin panel.
Look for “YouTube Showcase” and click Activate.

youtube, video, gallery, management, plugin, responsive, showcase, powerful, simple,

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Reffered: https://wordpress.org/