How to hide block while field in database is empty?
Part 1: Install the Rules block visibility module (and Rules)

You should be able to get this to work using the Rules block visibility module. Here is a quote from its project page:


  The Rules block visibility module allows Rules components to be used to control block visibility. This provides Drupal administrators and developers extreme flexibility in controlling when blocks should be displayed on their websites, in addition to the default visibility options provided by Drupal.
  
  The general idea is that if you can do it with Rules, you can use it to control block visibility, so the possibilities are limitless:
  
  
  Need to show a block only for users registered more than a month ago?
  Perhaps you have a block that must be shown only between 8am-5pm on weekdays?
  What about displaying or hiding a block based on current weather conditions?
  
  
  All of this can be done by using Rules block visibility.


With that, and as per the "if you can do it with Rules, you can use it to control block visibility" above, you've reduced your question to making Rules intercept the value of your field video (i.e. if it is empty or not).

Part 2: Create 2 appropriate Rules Components

The Rules block visibility module doesn't have a lot of documentation, except in the README.txt that comes with this module. Here is what the crucial part of it is (to get the idea):


  Configuration is done on a per-block basis. To control a block
  visibility using a rule component, go to the block settings page,
  scroll down to the "Rules" tab, and select the Rules component that
  you want to use.
  
  Notice that to be able to be used by this module, a Rules component
  must be constructed in a very specific way. See the next section for
  more information.


This module comes with 2 sample Rules Components, that should help to understand its concept.

By looking at these samples, I was able to create another Rules Component which looks like so:

{ "rules_block_visibility_hide_block_for_user_1" : {
    "LABEL" : "Hide block for user 1",
    "PLUGIN" : "rule",
    "OWNER" : "rules",
    "REQUIRES" : [ "rules" ],
    "USES VARIABLES" : {
      "module" : { "label" : "Module", "type" : "text" },
      "delta" : { "label" : "Delta", "type" : "text" },
      "result" : { "label" : "Result", "type" : "boolean", "parameter" : false }
    },
    "IF" : [
      { "NOT data_is" : { "data" : [ "site:current-user:uid" ], "value" : "1" } }
    ],
    "DO" : [ { "data_set" : { "data" : [ "result" ], "value" : "1" } } ],
    "PROVIDES VARIABLES" : [ "result" ]
  }
}


You should be able to import this rule in your own environment.

What this Rules Component does is "only" return a boolean (1 or 0), based on the condition if the user's uid is YES or NO equal to 1.

With that, we're coming close to an actual answer to your question: create 2 such Rules Components (1 for your block 1, and 1 for your block 2). And within each of those 2 Rules components, you only have to adapt the Rules Condition (as compared to my sample Rules Component here, apart probably from its machine name or so):


Rule 1 (which will be used to manage the visibility of Block 1) should have a condition like "field video is NOT empty".
Rule 2 (which will be used to manage the visibility of Block 2) should have a condition like "field video is empty".


Part 3: Set Block Visibility using the Rules Component

Head over to the "Block" settings for each of your 2 blocks. At the bottom of its settings, within the typical "Visibility settings", there is now (after you enabled the Rules block visibility module as in Part 1) an extra tab labeled "Rules". Using that tab will allow you to select a "Rules Component" that will do what's documented below that selection list field, ie: "Show this block only if the selected rule returns a positive value. Important: to be listed here, a block visibility rule must have specific parameters and return values.".

Obviously, all you have to do is select Rule 1 for Block 1, and Rule 2 for Block 2.

Note: it doesn't matter what type of block it is (created by a view, or something else), it works in all cases.