Video on Shiny Server

i install Shiny server on cEntos 7.
I uploaded several videos to the www folder.
i create a working application that shows the different videos based on a condition.

I deploy the application on shiny server but the videos don't work
Thanks
Alexander

What do your logs show ? errors ?
Is the app working / no errors but just blank of the video ? or does it show red text, or grey out ?
more info needed.
or a reprex...

Just blank videos.
do the same things even for picture.
that's the code:

#-------tabella previsioni-------
rm(list = ls())
library(shiny)
library(shinyjs)
library(shinyBS)




server = (function(input, output,session) {
    
      variabile<-reactiveValues(
                              attivita=1,
                              db_attivita=NULL)

    #------- VIDEO
    output$fasevid<-renderUI({
      db_attivita<-variabile$db_attivita
      attivita<-variabile$attivita
      if(!is.null(attivita)){
        if(attivita>nrow(db_attivita)){
        }else{
          HTML(
            paste0('<iframe width="1664px" heigth="880px" src="video/fase_',db_attivita$ID_ATT[attivita],'.mp4" ></iframe>')
          )
        }
      }
    })
  
})

db_attivita is NULL
ID_ATT wont be there ?

is the esemplify code

I think this is an issue with how the app is triggered.
I'm only using Rstudio IDE , not any server but still.

If the app has the code to create the app object like so :
shinyApp(ui, server)
then
if I launch the app via runApp() or the IDE's green run app button, I can get an iframe playing a mp4 from a video subfolder of www.
However if I launch the app via selecting the app.R code and submitting it into console, the src is not found.

If I select and submit all the app.R code, *except for * shinyApp(ui, server) , and then follow up by submitting shinyAppDir(".") again it works.